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Gould  and  Pyle's  Cyclopedia  of 
Practical  Medicine  and  Surgery 

Illustrated*        One    Volume 
With  74  Special  Contributors 


A  Concise  Reference  Handbook  (Alphabetically 
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panion volume,  which  should  be  the  same  trustworthy 
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P.    BLAKISTON'S   SON    &    CO.,    ::     Publishers 


PRACTICAL   TREATISE 


MECHANICAL  DENTISTRY 


BY 

JOSEPH    RICHARDSON,  M.D.,  D.D.S. 

LATE   PROFESSOR    OF   THE    PRINCIPLES   OF    PROSTHETIC    DENTISTRY  IN   THE   INDIANA   DENTAL   COLLEGE, 

ETC.,    ETC. 

SEVENTH   EDITION 

REVISED,    ENLARGED,    AND    EDITED   BY 

GEORGE   W.  WARREN,  A.M.,  D.D.S. 

PROFESSOR    OF    CLINICAL    DENTISTRY   AND    ORAL    SURGERY;      CHIEF    OF    THE    CLINICAL   STAFF,    PENNSYLVANIA 

COLLEGE    OF    DENTAL   SURGERY,   PHILADELPHIA;     AUTHOR   OF    "A    COMPEND    ON   DENTAL 

PATHOLOGY    AND    DENTAL    MEDICINE,"    AND   "  A    COMPEND   OF 

DENTAL    PROSTHESIS   AND   METALLURGY'." 


WITH  SIX  HUNDRED  AND  NINETY-ONE  ILLUSTRATIONS 

MANY  OF  WHICH  ARE  FROM  NEW  AND    ORIGINAL    DRAWINGS 


PHILADELPHIA 
P.    BLAKISTON'S   SON    &    CO. 

IOI2    WALNUT    STREET 
I9O3 


Entered  according  to  Act  of  Congress,  in  the  year  1897,  by 

P.  BLAKISTON,  SON  &  CO., 

In  the  Office  of  the  Librarian  of  Congress,  at  Washington,  D.  C. 


JbJft 


I  «  /  Q 


Co 


THE   MEMORY    OF   THE   LATE 

JAMES   TAYLOR,  M.D.,   D.D.S., 

FORMERLY   EMERITUS   PROFESSOR    OF   THE    INSTITUTES    OF    DENTAL   SCIENCE 
IN   THE    OHIO    COLLEGE   OF   DENTAL   SURGERY, 


ACKNOWLEDGMENT   OF   PROFESSIONAL   EMINENCE 
AND   PRIVATE  WORTH, 

Ctyis  Volumt  ts  gratefullg  inscrffieo, 

BY 
HIS   FORMER    PUPIL, 

THE   AUTHOR. 


NOTE. 

In  preparing  the  seventh  edition  of  this  work,  the  editor's  effort 
has  been  to  make  it  preeminently  practical  as  a  text-book  for 
students,  and  a  guide  for  young  practitioners, — an  exponent  of  the 
present  status  of  dental  prosthesis.  Much  of  the  text  has  been 
rewritten;  three  new  chapters,  new  appliances,  and  systems  have 
been  introduced;  while  useless  methods  and  obsolete  theories  have 
been  eliminated,  thus  keeping  the  dimensions  of  the  book  convenient 
and  compact. 

The  editor  desires  to  acknowledge  his  indebtedness  to  the  writ- 
ings of  Professors  Wilbur  F.  Litch,  C.  J.  Essig,  L.  P.  Haskell,  and 
Drs.  George  Evans,  James  W.  White,  Eben  F.  Flagg,  John  Allen, 

Theo.  F.  Chupein,  and  others. 

Geo.  W.  Warren. 

Philadelphia,  April,  1897. 


PREFACE  TO  FIFTH  EDITION. 


The  demand  for  a  fifth  edition  of  the  present  work,  following 
•closely  upon  the  publication  of  the  one  immediately  preceding, 
affords  gratifying  assurance  of  the  profession's  recognition  of  the 
treatise  as  a  trustworthy  exponent  of  the  present  status  of  pros- 
thetic dentistry  as  illustrated  in  the  practice  and  teachings  of  its 
representative  members. 

Not  less  obviously  does  it  furnish  proof  of  an  increasing  inter- 
est in  a  department  of  dental  practice  that  has  amply  vindicated 
its  claim  to  rank  as  a  conservative  branch  of  the  healing  art;  a  dis- 
tinction due,  in  large  part,  to  the  introduction  and  growth  of  more 
or  less  perfected  systems  of  root-crowning  and  bridge  dentures — 
systems  involving  processes  of  repair  and  methods  of  curative  treat- 
ment that  do  not  suffer  by  comparison  with  those  practised  at  the 
chair  in  the  important  work  of  restoring  to  usefulness  organs  whose 
natural  functions  have  been  impaired  or  wholly  subverted  by  the 
ravages  of  decay. 

It  is  a  suggestive  fact,  commended  to  the  consideration  of  those 
-who  characterize  prosthetic  dentistry  as  essentially  "  mechanical," 
and  who  seek  to  disparage  the  professional  and  scientific  qualifica- 
tions necessary  to  success  in  this  department,  that  the  results 
achieved  by  the  conservative  methods  alluded  to  have  been  reached 
only  through  a  critical  study  of  tooth-structure  and  function,  a 
familiar  acquaintance  with  pathological  conditions  associated  with 
diseased  teeth  and  implicated  tissues,  a  comprehensive  knowledge 
•of  the  curative  resources  of  dental  therapeutics,  a  broad  and  intelli- 
gent apprehension  of  principles  underlying  mechanical  devices,  and 
a  marvelous  development  of  ingenuity  and  manipulative  skill. 

For  obvious  reasons,  therefore,  large  space  is  given  to  the  con- 
sideration of  these  systems  of  crown  replacement,  the  value  and 
importance  of  which  command,  at  this  time,  general  and  deserved 
recognition.     Subjected  to  the  crucial  tests  of  time,  and  amenable 


X  PREFACE    TO    FIFTH    EDITION. 

to  the  inexorable  verdict  of  experience,  many  of  them,  doubtless, 
will  at  no  distant  day  take  their  place  "  down  among  the  dead 
men,"  while  others,  in  obedience  to  the  operation  of  laws  that  de- 
termine the  "  survival  of  the  fittest,"  will  live  and  take  a  fixed  place 
among  other  humane  devices  that  have  proved  lasting  benefactions 
to  mankind. 

Without  indicating  specifically  the  supplemental  contributions 
incorporated  in  this  edition,  it  will  be  sufficient  to  state  that  the 
work  has  been  materially  enriched  by  the  introduction  of  special 
methods  of  substitution,  and  various  laboratory  appliances,  so  con- 
spicuously meritorious  that  they  may  properly  be  said  to  mark  an 
era  in  the  development  of  prosthetic  practice. 

Joseph  Richardson. 

Terre  Haute,  Ind. 


CONTENTS. 


PAGE. 

Dedication,     v 

Editor's    Note, vii 

Preface,     ix 

Introduction,     17 


CHAPTER    I. 

Fuels,    - 22-30 

Liquid  Fuels  ;   Solid  Fuels  ;   Gaseous  Fuels. 


CHAPTER    II. 

Appliances  used  in  the  Generation  and  Application  of  Heat, 31-67 

Lamps  ;  Burners  ;  Blowpipes  ;  Supports  ;  Furnaces  ;  Heaters  ;  Crucibles  ; 
Principles  of  Soldering. 

CHAPTER    III. 

Metals   Employed   in    Dental   Laboratory   Operations, 68-73 

Gold,  Properties  of;  Properties  of  Particular  Alloys  of  Gold. 


CHAPTER    IV. 
Refining  Gold,  Elements  Employed,  etc., 74-79 

CHAPTER    V. 

Alloys  of  Gold  for  Dental  Purposes, 80-88 

Formulas  for  Gold  Plate  used  as  a  Base  for  Artificial  Dentures  ;  Clasps, 
Wire,  Stays  or  Backings,  Metal  Pins,  etc.  ;  Gold  Solders,  Formulas 
for  ;  Method  of  Reducing  Gold  to  a  Lower  or  Raising  to  a  Higher 
Standard  of  Fineness,  and  of  Determining  the  Carat  of  any  given 
Alloy. 

CHAPTER    VI. 

Method    of    Converting    Gold    Alloys    into    the    Required    Forms    for 

Dental    Purposes, 89-97 

Thickness  of  Gold  Plate  Required  as  a  Base  for  Artificial  Dentures, 
Clasps,  Backings,  etc. ;  Reduction  of  Gold  Solders  into  Proper 
Form  for  Use ;  Method  of  Obtaining  Gold  Wire,  Constructing 
Spiral  Springs,  etc. 

xi 


Xll  CONTENTS. 

CHAPTER    VII.  page. 

Silver,  General  Properties  of,  Alloys  of,  Refining  Alloys  of,  etc.,.  .  .   98-102 
Reduction  of  Silver  to  Required  Forms  for  Dental  Purposes ;  Formulas 
for  Silver  Solders. 

CHAPTER    VIII. 
Platinum,  Platinoid  Metals,  and  their  Alloys, 103-106 

CHAPTER    IX. 
Aluminium,  General  Properties  and  Alloys  of, 1 07-1 10 

CHAPTER    X. 
Copper,  Zinc,  Lead,  Tin,  Antimony,  and  Bismuth,  and  their  Alloys,.    111-116 

CHAPTER    XI. 

General  Properties  of  Alloys,  and  their  Treatment  and  Behavior 

in  the  Process  of  Compounding, 11 7-1 19 

CHAPTER    XII. 

Treatment  of  the  Mouth  Preparatory  to  the  Insertion  of  Artificial 
Dentures,  and  Time  Necessary  to  Elapse  After  the  Extrac- 
tion of  the  Teeth  Before  Inserting  Artificial  Dentures,....    120-125 

CHAPTER    XIII. 

Materials,  Appliances,  and  Methods  Employed  in  Obtaining  Impres- 
sions of  the  Mouth 126-147 

CHAPTER    XIV. 
Plaster  Models,  and  Manner  of  Obtaining  Same, 148-155 

CHAPTER    XV. 

Metallic  Dies  and  Counter-Dies  ;  Manner  of  Obtaining  ;  Essential 

Properties,    etc., 1 56-1 77 

CHAPTER    XVI. 

Partial  Dentures  Retained  in  the  Mouth  by  Means  of  Clasps  At- 
tached to  the  Natural  Teeth, 178-197 

Remarks  on  the  Use  of  Clasps  ;  The  Teeth  most  Suitable  for  Clasp- 
ing ;  Separation  of  the  Teeth  for  the  Reception  of  Clasps  ;  Modi- 
fications in  the  Form  of  Clasps ;  Modifications  in  the  Form  of 
Plates  for  Partial  Dentures  Supported  by  Clasps ;  Swaging  or 
Stamping  the  Plate,  etc. 

CHAPTER    XVII. 

Partial  Dentures  Supported  in  the  Mouth  by  Atmospheric  Pres- 
sure or  Adhesion  ;  Modifications  in  the  Form  of  the  Base, 
etc 198-201 


CONTENTS.  Xlll 

CHAPTER    XVIII.  page, 

Method  of  Obtaining  an  Antagonizing  Model  for  Partial  Dentures  ; 
Selecting,  Arranging,  and  Antagonizing  the  Teeth  ;  Investing, 
Adjusting   Stays,    Soldering,   etc., •  •  •   202-212 

CHAPTER    XIX. 

Entire    Dentures, 213-232 

A  Consideration  of  the  Principles  and  Attendant  Phenomena  In- 
volved in  the  Application  of  the  Forces  Utilized  as  a  Means 
of  Attachment;  Esthetic  Requirements  in  the  Selection  and  Ar- 
rangement of  the  Teeth  of  Replacement;  The  Four  Basal  Tem- 
peraments and  their  General  Indications ;  The  Teeth  as  Indicated 
by  Temperament;  Temperament  in  Relation  to  the  Teeth. 

CHAPTER    XX. 
Entire  Dentures  Attached  to  a  Swaged  Metallic  Plate  Base, 233-257 

CHAPTER    XXI. 
Manufacture  of  Porcelain  Teeth, 258-263 

CHAPTER    XXII. 
"  Continuous-Gum  "    Dentures, 264-280 

CHAPTER    XXIII. 
Rubber  or  Vulcanite  Base, 281-326 

CHAPTER    XXIV. 
Celluloid    Base, 327~353 

CHAPTER    XXV. 
Attaching  Porcelain  Teeth  to  a  Metallic  Base  with  Rubber  or  Cel- 
luloid,         354-36i 

CHAPTER    XXVI. 
Cast  Metal  Base, 362-372 

CHAPTER    XXVII. 
Defects  of  the  Palatal  Organs  and  their  Treatment  by  Artificial 

Means, 373-399 

CHAPTER    XXVIII. 
Appliances  for  the  Correction  of  Fractured  Maxillje   (Interdental 

Splints),     400-433 


XIV  CONTENTS. 

CHAPTER    XXIX.  PAGE. 

Appliances  for  the  Correction  of  Dental  Irregularities, 434-473 

CHAPTER    XXX. 
Artificial    Crowns, 474-55 1 

CHAPTER    XXXI. 
Bridge    Dentures,  . .  . 552-654 

CHAPTER    XXXII. 
Electricity,  and  its  Application  in  Dental  Mechanics, 655-670 


A  TREATISE 


MECHANICAL   DENTISTRY. 


INTRODUCTION. 

Before  entering  upon  a  detailed  account  of  the  agencies,  pro- 
cesses, and  methods  appertaining  to  the  department  of  dental 
practice  to  which  this  work  relates,  some  general  reflections  may 
not  be  inappropriate. 

It  is  not  the  purpose  of  the  writer  to  unduly  magnify  the  claims 
of  prosthetic  dentistry  upon  the  regard  and  consideration  of  the 
profession.  A  just  estimate  of  the  nature  of  its  requirements,  and 
the  results  contemplated  in  its  practice,  as  well  as  the  abundance 
and  sufficiency  of  its  resources  in  the  accomplishment  of  its  high 
and  humane  purposes,  will,  it  is  believed,  amply  vindicate  its  im- 
portance, its  possibilities,  and  its  beneficence  as  a  department  of 
practical  dentistry  having  intimate  relation  to  the  necessities  of 
the  unfortunate. 

The  untimely  or  premature  loss  of  the  natural  teeth  may  be 
ascribed  to  a  number  of  diverse  causes.  Multitudes  are  lost  in 
consequence  of  abuse  or  neglect,  or  the  dread  of  pain  so  com- 
monly associated  with  the  means  employed  in  their  preservation ; 
many  from  unavoidable  accident ;  and  countless  numbers  are  sac- 
rificed through  the  incompetency  and  dishonesty  of  ignorant  and 
unscrupulous  operators  who,  in  one  guise  or  another,  infest  and 
prey  upon  communities. 

Nor  can  we  exclude  from  this  list  of  causes  another  source 
of  loss  which,  by  implication,  declares  the  impotence  of  the  pro- 
fession's curative  resources  in  the  absolute  conservation  of  these 

2  jy 


1 8  MECHANICAL   DENTISTRY. 

important  organs.  Whatever  sense  of  humiliation  may  attend  the 
statement,  it  is  nevertheless  true  that  the  highest  attainable  skill 
directed  to  the  permanent  preservation  of  the  natural  teeth  must, 
in  the  very  nature  of  things,  often  prove  inadequate  and  abortive, 
for  no  proposition  is  more  broadly  or  more  generally  recognized 
by  intelligent  practitioners  than  that  conservative  practice  has  its 
limitations  growing  out  of  conditions  associated  with  individual 
organisms  and  environments  wholly  beyond  the  control  of  the 
operator.  Whatever  triumphs  (and  they  are  many  and  conspicu- 
ous) modern  conservative  dentistry  may  have  achieved  in  the  way 
of  narrowing  the  field  of  prosthetic  practice,  the  prophecy,  born  of 
hope,  that  the  time  will  come  when  the  utmost  resources  of  human 
skill  will,  in  respect  of  the  teeth,  be  able  to  exempt  mankind 
wholly  from  the  penalties  of  transgressed  law,  is  as  Utopian  and 
delusive  as  the  faith  that  prophylactic  or  preventive  medicine  will 
ultimately  eradicate  every  form  of  disease  that  at  present  afflicts 
mankind.  They  are  alike  the  dreams  of  enthusiasts  and  vision- 
aries. Physical  infirmity,  in  one  form  or  another,  is  the  heritage  of 
the  race,  and  human  skill,  however  well  directed  or  conscientiously 
and  intelligently  administered,  can  do  little  more  than  mitigate  the 
"pains  and  penalties"  of  the  primal  curse  that  rests  upon  all. 

It  is  the  peculiar  and  distinctive  prerogative  of  prosthetic  den- 
tistry to  devise  and  perfect  means  for  the  amelioration  of  the  con- 
dition of  those  who,  from  whatever  cause,  have  suffered  one  of  the 
gravest  forms  of  mutilation  in  the  loss  of  organs  so  essential  to  the 
healthful  performance  of  many  important  functions.  In  this  spe- 
cial field  of  humane  endeavor  the  highest  order  of  qualification  is 
imperatively  demanded  for  the  complete  fulfilment  of  its  diversi- 
fied and  complex  requirements.  No  one  can  be  said  to  be  properly 
equipped  for  its  duties  who  has  not  a  more  or  less  familiar  ac- 
quaintance with  such  of  the  several  branches  of  Physics  and 
Natural  Philosophy  as  relate  in  any  manner  to  his  special  work, 
while  an  exact  knowledge  of  the  Anatomy,  Physiology,  and  Path- 
ology of  the  tissues  or  structures  in  any  way  related  to  the  substi- 
tute is  absolutely  indispensable.  Added  to  such  qualifications  is 
the  essential  requirement  of  the  highest  order  of  manipulative 
skill.  But  beyond  all  these  qualifications,  and  supplementing 
them,  is  that  art  culture  which  is  the  crown  and  inspiration  of  all 
perfect  work  in  every  form  of  substitution,  and  without  which  the 


INTRODUCTION. 


19 


best  results  of  mere  handcraft  are,  in  the  main,  but  little  better  than 
libels  and  caricatures.  In  no  other  department  of  practical  dentis- 
try is  the  art  instinct  so  strongly  appealed  to,  or  so  imperiously 
demanded  as  a  condition  of  the  highest  success.  Dr.  Eben  M. 
Flagg,  in  an  essay  on  Dental  Art,  very  aptly  says:  "There  is  an 
element  which  enters  into  the  conception  and  execution  of  every 
branch  of  our  labor,  and  more  or  less  forms  part  of  every  opera- 
tion that  we  are  called  upon  to  make,  be  it  surgical,  operative,  or 
prosthetic.  This  element  lightens  our  drudgery,  enlarges  our 
souls,  gives  individuality  to  our  work,  and  brings  satisfaction  to 
ourselves  that  fully  repays  the  time  spent  in  fulfilling  its  require- 
ments. It  was  born  with  our  race,  and  has  inseparably  accompa- 
nied every  movement  that  has  brought  comfort  and  happiness  to 
man.  It  has  contributed  its  share  toward  raising  the  physician 
from  a  mere  'bleeding,  physicking,  leeching'  animal,  to  the  posi- 
tion he  occupies  to-day,  and  has  shown  the  mechanic  and  inventor 
that,  if  he  would  be  great,  he  must  be  more  than  an  artisan ;  he 
must  be  an  artist.  This  element — the  element  of  art — whenever 
it  enters  the  field  of  human  life,  has  for  its  function  to  finish  and 
render  attractive  the  hard  labor  that  preceded  it.  Thus,  we  do 
not  find  it  in  its  full  manifestation  except  in  those  departments 
of  labor  which  have  attained  scientific  certainty." 

Among  the  unnumbered  millions  of  human  beings  who  have 
.peopled  the  earth  since  the  dawn  of  time,  it  may  be  affirmed  that 
no  two  have  been  created  with  faces  exactly  alike.  There  is  the 
same  aggregate  of  features,  and  a  pervading  general  resemblance 
of  one  person  to  another,  but  there  will  be  found  as  infinite  a  multi- 
plication of  distinct  shades  of  facial  expression  as  there  are  human 
faces,  and  each  separate  shade  of  expression  characteristic  of  each 
one,  and  distinguishing  him  or  her  from  all  others,  constitutes  fa- 
cial individuality.  Each  separate  feature — as  the  eye,  the  nose,  the 
mouth,  the  teeth,  facial  contour,  complexion,  temperament,  etc. — 
contributes  to  this  individuality,  and  no  one  special  feature  more, 
perhaps,  than  the  teeth.  There  are  few  more  repulsive  deformities 
than  those  inflicted  by  the  loss  of  these  organs,  and  none  more  fa- 
tal to  the  habitual  and  characteristic  expression  of  the  individual. 
It  is  the  special  mission,  as  it  is  the  first  and  highest  duty,  of  the 
dentist  to  preserve  this  individuality  intact,  and  an  equally  impera- 
tive duty  to  restore  it  as  perfectly  as  possible  when  impaired.     To 


20  MECHANICAL   DENTISTRY. 

fulfil,  in  the  most  perfect  manner  possible,  this  most  difficult  of 
all  the  requirements  of  prosthetic  practice  implies  an  art  culture 
that  is  competent  to  interpret  the  distinct  play  of  features  asso- 
ciated with  individual  physiognomies,  to  differentiate  individual 
temperaments,  and  make  available  the  sculptor's  and  painter's 
perceptions  of  the  subtle  harmonies  of  form  and  color. 

To  the  failure  or  inability  to  properly  comprehend  the  practical 
import  or  significance  of  individual  characteristics,  so  far  as  they 
find  expression  in  the  teeth,  and  the  consequent  failure  to  con- 
form our  methods  of  replacement  to  the  imperative  requirements 
of  art,  may  be  fairly  ascribed  the  deserved  reproach  into  which 
prosthetic  practice  has  fallen,  and  not,  as  is  generally  charged,  to 
the  employment  of  any  particular  material  or  methods  concerned 
in  the  mechanical  execution  of  the  work. 

There  is  no  material  classed  among  the  so-called  "cheap  bases" 
that  does  not  embody  art  possibilities  far  beyond  what  is  being 
continually  illustrated  in  general  practice.  Unquestionably  they 
are  not  the  best  for  the  purpose,  but  they  may  be  greatly  en- 
hanced in  value,  and  rendered  more  deserving  of  professional 
favor,  if  utilized  in  conformity  with  the  esthetic  requirements  im- 
peratively demanded  in  all  forms  of  substitution. 

There  is  an  ethical  phase  of  this  subject  which  must  enter  as  an 
element  into  the  profession's  estimate  of  the  suitableness  of  these 
inferior  forms  of  replacement — a  question  of  obligation  and  re- . 
sponsibility  involving  a  problem  the  solution  of  which  should  be 
attempted  without  unreasonable  prejudice  or  unjust  discrimina- 
tion so  far  as  materials  and  methods  are  concerned.  There  are 
multitudes  in  every  community  who,  though  not  in  indigent  cir- 
cumstances, are  unable  to  secure  expensive  services  without  great 
hardship,  and  other  multitudes  who  perforce  must  suffer  lasting 
harm  and  prolonged  deformity  on  the  same  terms.  Dentistry,  like 
Medicine,  is  professedly  a  humane  calling,  and  it  would  be  well  to 
consider  whether  the  afflicted  have  not  just  claims  upon  the  pro- 
fession's resources  in  providing  them  with  inexpensive  means  of 
relief.  Until  the  time  comes  when  the  necessities  of  this  class  can 
be  supplied  with  wholly  unobjectionable  forms  of  substitution  at  a 
cost  that  is  not  oppressive,  or  that  does  not  altogether  deny  relief, 
it  will  be  well  to  cease  indiscriminate  condemnation  of  materials 
and  methods  which,  when  properly  considered  in  relation  to  their 


INTRODUCTION.  2E 

yet  undeveloped  possibilities,  are  far  from  being  unmixed  evils. 
That  there  are  radical  and  inherent  objections  to  the  use  of  vege- 
table plastics  that  do  not  attach  to  metallic  bases  is  unquestion- 
able, but  it  is  equally  true  that  the  nature,  behavior,  and  proper  or 
scientific  treatment  of  these  substances  have  not  been,  until  quite 
recently,  well  understood ;  that  imperfect  appliances  have  hereto- 
fore failed  to  develop  their  best  qualities,  and,  above  all,  that  there 
is  a  prevailing  disregard  or  ignorance  of  all  esthetic  requirements 
in  the  uses  to  which  they  are  applied.  That  the  facility  they 
afford  for  the  ready  construction  of  substitutes  has  attracted  to 
the  ranks  of  the  profession  a  mercenary  and  unscrupulous  class  of 
operators,  is  as  true  as  it  is  unfortunate.  However  powerless  the 
profession  may  have  been  in  the  past  to  check  this  evil,  the  re- 
sponsibility for  its  continuance  in  the  future  will  rest  largely  with 
the  profession  itself.  There  is  a  reasonable  assurance  that  the 
era  of  irresponsible  quackery  is  fast  passing  away.  The  people 
of  three-fourths  of  the  States  of  the  Union  have,  through  their 
representatives,  generously  and  confidingly  relegated  to  the  pro- 
fession the  power  of  providing  a  remedy  for  the  evils  of  char- 
latanry, and  have,  under  legal  forms,  designated  our  colleges  and 
boards  of  examiners  as  the  proper  custodians  of  the  profession's 
honor  and  the  people's  interest.  A  faithful  execution  of  the  trust 
reposed  in  these  bodies  will  go  far  to  redeem  prosthetic  practice 
from  the  undeserved  reproach  brought  upon  it  by  a  prostitution 
of  its  legitimate  resources  wholly  unworthy  of  toleration  and  ut- 
terly destructive  of  all  sense  of  professional  self-respect. 


CHAPTER  I. 

FUELS  EMPLOYED  IN  LABORATORY  PROCESSES. 

It  is  essential  that  the  mechanical  operator  should  have  some 
intelligent  conception  of  the  nature  and  properties  of  such  com^- 
bustible  substances  as  are  ordinarily  used  in  the  dental  laboratory 
for  the  generation  of  heat.  This,  and  a  somewhat  familiar  ac- 
quaintance with  approved  appliances  used  in  the  application  of 
heat  and  adapted  to  his  peculiar  needs,  are  indispensable  requis- 
ites to  the  successful  practice  of  the  department  of  practical  den- 
tistry to  which  this  work  relates.  Only  such  heat-producing  sub- 
stances as  are  deemed  suitable  for  dental  laboratory  operations 
will  be  considered  with  any  degree  of  particularity. 

The  general  forms  of  fuel  may  be  classified  as  Liquid,  Solid,  and 
Gaseous.  They  will  be  treated  of,  in  more  or  less  detail,  under 
these  general  heads. 

LIQUID    FUELS. 

In  connection  with  lamps  designed  chiefly  for  soldering  pur- 
poses and  vulcanizing,  the  substances  usually  employed  are  alco- 
hol, gasolene,  or  kerosene.  When  alcohol  is  employed,  the  lamp 
shown  in  Fig.  I  is  found  very  convenient  and  useful.  Gasolene  is 
used  in  connection  with  the  Oxycarbon  Forge  (see  page  43), 
while  good  kerosene,  uncontaminated  with  naphtha,  may  be  used 
with  safety,  and  is,  in  many  cases,  a  valuable  substitute  for  other 
combustible  materials  for  general  heating  purposes,  and  is  largely 
employed  in  connection  with  vulcanite  and  celluloid  work  by 
those  unable  to  command  the  ordinary  illuminating  gas. 

SOLID    FUELS. 

Under  this  head  are  comprehended  such  combustible  substances 
as  are  used  for  fires  or  draft  furnaces,  as  wood,  charcoal,  bitumin- 
ous and  anthracite  coal,  and  coke.  For  baking  or  muffle  furnaces 
used  in  tin-  construction  of  continuous-gum  work 'and  other  allied 
processes,  anthracite  and  coke  are  esteemed  the  most  suitable  on 

22 


FUELS    EMPLOYED   IN    LABORATORY    PROCESSES.  23 

account  of  the  high  temperatures  attainable  in  their  use,  and  the 
persistent  or  prolonged  heat  consequent  on  the  comparatively 
slow  waste  of  substance  in  the  process  of  combustion. 

Wood,  except  when  charred,  is  wholly  unsuited  for  laboratory 
work. 

Charcoal  is  the  solid  residuum  of  the  destructive  distillation  of 
wood.  It  is  obtained  by  igniting  wood,  and  then  excluding  it 
from  the  air  while  burning;  the  volatile  products  are  thus  driven 
off,  while  the  carbon  remains.  The  chemical  composition  of  the 
ordinary  charcoal  of  commerce  is  given  in  the  following  table,  in 
which  it  will  be  seen  to  consist  principally  of  carbon,  combined 
with  certain  volatile  constituents,  a  considerable  percentage  of 
absorbed  water,  and  but  little  ash : 

Carbon,    70  Nitrogen,   1 

Hydrogen,    5  Ash,    2 

Oxygen,    11  Hygroscopic  moisture,    ....    11 

During  the  process  of  charring,  the  volatile  constituents — hy- 
drogen, oxygen,  and  nitrogen — are,  in  a  large  measure,  driven  off, 
but  no  temperature  that  can  be  commanded,  and  no  time,  how- 
ever prolonged,  will  wholly  expel  them. 

Charcoal  is  insipid  and  inodorous,  is  a  poor  conductor  of  heat 
and  a  good  conductor  of  electricity,  is  insoluble  in  water,  is  at- 
tacked by  nitric  acid  with  difficulty,  and  is  but  little  affected  by 
the  other  acids  or  by  alkalies.  Its  carbon  constituent  is  exceed- 
ingly refractory  to  heat,  and,  if  secluded  in  a  retort,  will  neither 
fuse  nor  volatilize  under  the  highest  temperature  that  can  be  pro- 
duced. This  latter  property  of  carbon,  in  connection  with  that 
of  its  comparative  non-conduction  of  heat,  makes  it  a  valuable  in- 
gredient in  the  construction  of  supports  used  in  soldering,  repre- 
sented in  the  carbon  block  and  cylinder  (Figs.  27,  28),  and  in  the 
devices  (Figs.  50,  51)  combining  crucible  and  ingot  mold.  Char- 
coal retains  the  organic  structure  of  the  wood  from  which  it  was 
produced,  except  when  prepared  at  a  very  high  temperature,  when 
it  becomes  a  black,  shining,  porous  mass,  resembling  fossil  coal, 
with  a  considerable  increase  in  density  and  without  a  trace  of 
organic  structure. 

When  it  is  desired  to  maintain  a  high  heat  in  a  small  compass, 
the  charcoal  best  adapted  to  the  purpose  is  that  obtained  from 
what  is  termed  hard  wood,  as  the  beech,  the  oak,  the  alder,  the 


24  MECHANICAL   DENTISTRY. 

birch,  the  elm,  etc.  A  cubic  foot  of  charcoal  derived  from  these 
woods  weighs,  upon  an  average,  from  12  to  13  pounds,  while 
a  similar  bulk  obtained  from  soft  wood,  as  the  fir,  the  different 
kinds  of  pine,  the  larch,  the  linden,  the  willow,  and  the  poplar, 
averages  only  from  eight  to  nine  pounds.*  There  is,  therefore, 
economy  in  the  use  of  the  former  when  purchased  in  bulk ;  and  of 
this  class  the  beech-wood  charcoal  is  the  best  on  account  of  its 
greater  specific  gravity.  Charcoals  derived  from  the  hard  woods 
possess  the  additional  advantage  of  generating  a  more  equable 
and  enduring  temperature,  and  are,  therefore,  better  adapted  to 
operations  in  the  laboratory  requiring  a  prolonged  heat.  The 
more  heavy  charcoals  require  a  stronger  draft  than  those  of  a 
lighter  character,  as  a  more  generous  supply  of  oxygen  is  neces- 
sary to  their  perfect  combustion.  Charcoal  should  be  kept  as  dry 
as  practicable,  since  it  readily  absorbs  moisture  from  the  atmos- 
phere, by  which  its  calorific  energy  is  materially  impaired. 

Bituminous,  or  pit  coals,  are  generally  unfit  for  the  uses  re- 
quired of  fuel  by  the  dentist,  on  account  of  the  excessive  carbona- 
ceous residue  accompanying  their  combustion,  and  are,  therefore, 
seldom  used  except  when  reduced  to  that  form  of  mineral  char- 
coal known  as  coke. 

As  charcoal,  coke,  or  a  mixture  of  the  two,  and  anthracite  coal 
are  the  heat-producing  substances  chiefly  used  in  the  processes 
of  the  dental  laboratory  requiring  the  employment  of  solid  fuels, 
they  will  be  more  particularly  described. 

Coke. — This  substance  is  a  carbonaceous  product  obtained  from 
bituminous  coal  that  has  been  exposed  to  ignition  for  some  time, 
excluded  from  the  contact  of  air,  the  volatile  constituents  of  the 
coal,  like  those  of  wood, having  been  driven  off  by  the  heat.  There 
are  two  different  varieties  of  this  mineral  charcoal,  namely,  gas 
coke,  obtained  from'  the  retorts  of  gas  works  after  the  gases  have 
been  separated ;  and  oven  coke,  which  is  made  in  ovens  or  pits, 
and  which  is  considered  by  manufacturers  as  the  only  true  coke, 
gas  coke  being  merely  cinder.  There  is  a  marked  difference  in  the 
appearance  of  the  two  kinds  of  coke,  the  principal  part  of  that 
obtained  from  gas  houses  being  of  a  dull,  iron-black  color,  very 
spongy  and  friable,  is  more  rapidly  consumed  in  the  process  of 


*Ure. 


FUELS    EMPLOYED   IN    LABORATORY    PROCESSES.  25 

combustion,  and  produces  less  heat  than  the  harder  .and  more 
compact  variety.  The  best  coke  for  heating  purposes  is  the  oven 
or  pit  coke,  which  has  a  steel-gray  color,  with  somewhat  metallic 
luster,  is  compact  in  structure,  and  splits  into  pieces  having  a 
longitudinal  fracture.  Whenever  it  can  be  procured,  the  latter 
should  always  be  preferred  in  connection  with  the  use  of  the  bak- 
ing or  muffle  furnaces  employed  in  the  fabrication  of  continuous- 
gum  work,  porcelain  teeth,  etc.  Until  the  more  recent  substitu- 
tion of  anthracite,  the  former  was  exclusively  employed  for  these 
purposes,  and  is  in  every  way  suitable  in  the  production  of  high 
and  persistent  temperatures.  It  is  sometimes  used  combined 
with  charcoal,  but,  when  fairly  ignited,  gives  an  augmented  and 
more  lasting  heat  when  used  alone. 

Coke  does  not  readily  ignite,  and  at  first  generally  requires  the 
admixture  of  charcoal  to  effect  its  combustion ;  it  also  requires  a 
strong  draft  to  burn  it,  but  when  thoroughly  ignited  it  produces 
an  intense  and  persistent  heat.  As  before  stated,  it  is  one  of  the 
principal  fuels  used  in  baking  mineral  teeth,  porcelain  blocks, 
and  the  silicious  compounds  employed  in  the  construction  of  con- 
tinuous-gum work. 

Professor  Piggot,  in  his  remarks  on  the  comparative  value  of 
fuels,  observes:  "Practically,  for  the  purpose  of  the  chemist,  the 
best  fuel  is  charcoal  or  coke,  or  a  mixture  of  the  two.  The  ash  of 
charcoal  being  infusible,  it  passes  through  the  bars  of  the  grate  as 
a  white  powder.  Should  potash,  however,  be  in  large  excess,  it 
corrodes  the  bricks  by  forming  with  them  a  silicate  of  potash, 
which  runs  down  the  walls  and  chokes  the  bars.  In  small  quanti- 
ties this  action  is  beneficial,  as  it  furnishes  a  protective  varnish, 
and  unites  the  bricks  and  lutes  by  forming  a  sort  of  cement,  which 
intimately  combines  with  them. 

"Coke  contains  a  very  variable  amount  of  ash,  which  is  com- 
posed chiefly  of  oxid  of  iron  and  clay.  When  pure  it  forms  a 
harmless  slag,  which  injures  neither  the  furnace  nor  the  crucibles. 
Usually,  however,  the  oxid  of  iron  predominates.  In  this  case 
the  ash  is  very  injurious,  for  it  is  reduced  to  a  protoxid,  which  is 
not  only  fusible,  but  powerfully  corrosive  to  all  argillaceous  mat- 
ters, so  that  both  the  crucibles  and  furnaces  suffer."* 

*  "  Dental    Chemistry   and   Metallurgy." 


26  MECHANICAL   DENTISTRY. 

Anthracite. — Anthracite  is  the  most  condensed  variety  of 
mineral  coal,  containing  the  largest  proportion  of  carbon  and  the 
smallest  quantity  of  volatile  matter.  With  the  exception  of  the 
diamond,  it  is  the  purest  form  of  carbon  in  its  natural  state.  The 
best  specimens  contain  95  per  cent,  carbon,  but  the  average  pro- 
duction of  the  purest  beds  of  this  coal  will  not  exceed  90  per  cent., 
and  generally  not  more  than  80  to  87  per  cent,  carbon.  The  volatile 
matter  in  the  dense,  hard  varieties,  is  almost  exclusively  water  and 
earthy  impurities,  but  in  common  varieties  the  volatile  portion 
consists  of  water, hydrogen, oxygen,  and  nitrogen,  while  the  ash  or 
incombustible  matter  contains  oxid  of  iron,  iron  pyrites,  silica,  alu- 
mina, magnesia,  lime,  etc.  Anthracite  which  contains  only  80  per 
cent,  carbon,  with  20  per  cent,  water  and  incombustible  matter, 
is  the  lowest  grade  of  commercial  coal,  and  of  little  value  as  fuel. 

The  general  features  and  fractures  of  hard  anthracite  are  pecu- 
liar and  noticeable  to  the  common  observer.  They  are  massive, 
hard,  dense,  amorphous  or  conchoidal  in  fracture,  with  fine,  sharp 
edges  when  broken,  and  a  rich  satin  or  an  iron-black  sub-metallic 
luster.  With  some  local  exceptions  the  softer  varieties,  both  red- 
and  white-ash  (by  which  name  the  Pennsylvania  anthracite  coals 
are  generally  known),  are  less  massive,  hard,  and  dense,  more 
regular  and  cubical  in  fracture,  and,  exclusive  of  the  upper  red- 
ash  beds,  less  rich  and  lustrous. 

Anthracite  coals,  in  greater  or  less  abundance,  and  of  varying 
qualities,  are  found  in  several  of  the  States  and  territories  of  the 
Union,  namely,  in  Pennsylvania,  Massachusetts,  Rhode  Island, 
Virginia,  Arkansas,  Oregon,  and  in  New  Mexico  and  Sonora.  Of 
the  European  anthracite  fields,  exclusive  of  those  in  Wales,  Eng- 
land, the  most  prolific  and  largely  developed  are  those  in  France, 
while  others  of  more  limited  production  are  found  in  Spain,  Por- 
tugal, Germany,  Austria,  and  Norway.  Anthracite  also  exists  in 
Persia,  India,  China,  and  in  South  America.  The  most  prominent 
anthracite  fields  of  the  world,  however,  are  those  of  Pennsylvania 
and  South  Wales,  which  produce  nine-tenths  of  the  quantity  used. 

The  first  authentic  account  which  we  find  of  the  use  of  anthracite 
in  the  United  States  was  in  1768-69,  when  it  was  used  by  two 
blacksmiths  from  Connecticut, named  Gore.  It  did  not,on  account 
of  the  difficulty  of  making  it  burn,  come  into  use  for  domestic  pur- 
poses till  1808,  when  Judge  Fell  succeeded  in  burning  "stone  coal" 


FUELS    EMPLOYED    IN    LABORATORY    PROCESSES.  27 

in  a  grate  of  his  own  construction.  This  was  probably  the  first 
successful  use  of  anthracite  for  general  purposes  in  the  world. 
So  imperfectly  were  the  properties  of  this  fuel  understood,  and  so 
little  known  of  its  proper  management,  that  four  years  later,  Col. 
Shoemaker,  who  had  disposed  of  several  loads  of  it  to  parties  in 
Philadelphia  who  were  unable  to  burn  it,  was  arrested,  upon  a 
writ  obtained  from  the  city  authorities,  as  an  impostor  and  swind- 
ler, who  had  sold  them  rocks  for  coal. 

Prof.  H.  D.  Rogers  explains  the  formation  of  anthracite  by  sup- 
posing it  to  be  the  result  of  altered  bituminous  coal  metamor- 
phosed by  intense  heat,  and,  of  course,  by  heat  induced  subse- 
quent to  the  formation  of  the  bituminous  beds ;  and  he  further 
explains  the  escape  of  the  volatile  portion  of  the  latter  as  gas 
through  cracks  and  openings  caused  by  the  plication  of  the  an- 
thracite strata.  This  plication  follows  closely  the  general  type 
of  the  paleozoic  rocks,  which  are  intensely  crushed  and  folded 
near  the  contact  of  their  edges  with  the  igneous  or  granitic  rocks, 
and  much  less  plicated  and  distorted  in  a  western  direction.  This 
theory,  though  natural  and  ingenious,  is  controverted  by  others 
who  contend  that  anthracite  is  not  a  metamorphosis  of  bitumin- 
ous coal,  but  as  much  a  normal  creation  as  the  bituminous  variety 
itself,  from  a  combination  of  its  constituents  under  superior  heat, 
however  the  original  elements  were  produced. 

The  particular  mineral  fuel  under  consideration  has  been  treated 
of  here  somewhat  at  length,  for  the  reason  that  it  is  being  more 
generally  employed  of  late  years  by  the  dentist,  not  only  for  re- 
fining and  general  heating  purposes,  but  more  especially  in  those 
important  processes  of  the  dental  laboratory  in  which  more  or 
less  refractory  silicious  substances  requiring  a  high,  uniform,  and 
prolonged  heat,  are  employed  in  compounding  body  and  gum 
enamels,  in  baking  mineral  teeth,  and  in  the  construction  of  con- 
tinuous-gum work.  For  the  latter  especially,  it  is  preferred  by 
many  to  coke,  in  connection  with  solid  fuel  furnaces. 

Owing  to  the  difficulty  of  igniting  anthracite,  it  is  customary  to 
mix  with  it  at  first  about  an  equal  quantity  of  charcoal.  Its  proper 
combustion  after  ignition,  when  burned  alone,  requires  a  strong 
draft,  which  is  ordinarily  attainable  in  use  of  the  ordinary  draft  or 
muffle  furnace  properly  connected  with  a  suitable  flue.  Under  con- 
ditions that  insure  more  or  less  complete  combustion,  the  chief  of 


28  •  MECHANICAL   DENTISTRY. 

which  is  a  generous  supply  of  oxygen,  anthracite  will  yield  a 
higher  temperature  than  any  other  kind  of  solid  fuel.  The  blast 
furnace  is,  therefore,  best  adapted  to  this  end,  though  for  all  ordi- 
nary purposes  requiring  heat  in  the  dental  laboratory  the  ordinary 
chimney  draft  will  be  sufficient.  To  recapitulate  somewhat,  it  may 
be  said,  not  only  in  reference  to  anthracite,  but  to  the  other  solid 
fuels  mentioned,  that  in  order  that  the  greatest  amount  of  heat  may 
be  generated,  it  is  necessary  that  the  conditions  essential  to  their 
most  perfect  combustion  should  be  strictly  observed ;  these,  as  be- 
fore stated,  have  reference  mainly  to  an  unobstructed  circulation 
of  air  in  order  that  oxygen  may  be  freely  supplied  to  them.  To 
this  end  the  furnace  should  be  kept  clean,  the  bars  of  the  grate 
unbroken,  and  a  good  draft  obtained.  The  condition  in  which  the 
fuel  is  applied  will  also  modify  the  results.  Thus,  for  example,  if 
the  lumps  are  too  large,  they  will  absorb  heat,  and  caloric  will  be 
lost ;  if  too  small,  they  will  be  too  rapidly  consumed.  It  is  essen- 
tial, also,  to  have  the  fuel  as  free  as  possible  from  dust  and  dirt,  as 
these  fine  particles  in  any  considerable  quantities  obstruct  the 
draft,  and  prevent  a  thorough  ignition  of  the  mass.  Coke,  espe- 
cially, should  be  preserved  clean,  and  should  be  broken  into  frag- 
ments not  larger  than  an  inch  or  an  inch  and  a  half  in  diameter,, 
and,  as  nearly  as  possible,  in  the  form  of  blocks  or  cubes,  as  these 
leave  more  open  spaces  for  the  free  circulation  of  air. 

GASEOUS    FUEL. 

Illuminating  Gas. — The  ordinary  illuminating  gas,  derived  from 
the  destructive  distillation  of  bituminous  coals,  is  a  form  of  fuel 
that,  of  late  years,  has  largely  supplanted  the  use  of  the  liquid  and 
solid  varieties  for  heating  purposes  in  the  dental  laboratory.  The 
introduction  of  gas,  for  the  uses  indicated,  marks  an  era  in  pros- 
thetic practice,  so  far  as  the  application  of  heat  for  metallurgic 
purposes  is  concerned,  in  which  inventive  genius  has  been  indus- 
triously and  successively  employed  in  devising  and  perfecting  ap- 
pliances designed  to  obviate  entirely  the  necessity  of  employing 
other  forms  of  fuel  heretofore  used,  and  which  are,  in  many  re- 
spects, inconvenient  and  objectionable.  So  fruitful  have  been  these 
later  devices  in  meeting  the  necessities  of  the  dental  metallurgist, 
and  so  reasonably  certain  is  it  that  more  extended  experiments  in 
the  construction  of  furnaces  adapted  to  this  mode  of  producing 


FUELS    EMPLOYED    IN    LABORATORY    PROCESSES.  2Q 

heat  will,  in  the  near  future,  meet  all  the  requirements  of  ceramic 
art,  as  applied  to  dental  prosthetics,  that  it  may  be  confidently  pre- 
dicted that  all  solid  fuels  for  these  purposes  will  be  wholly  ban- 
ished from  the  laboratory  wherever  gas  can  be  commanded  for 
the  generation  of  heat.  The  latter,  intermixed  with  atmospheric 
air  in  proper  proportions,  and  used  in  connection  with  burners  and 
furnaces  of  suitable  construction,  is,  in  all  essential  respects,  pref- 
erable, since  it  is  comparatively  free  from  dirt  and  smoke,  and  is 
capable  of  producing  a  rapid,  equable,  and  intense  heat,  which  is 
completely  under  the  control  of  the  operator  as  respects  duration 
and  the  degree  of  temperature  required  for  any  given  operation. 

Natural  gas  has,  until  recently,  been  obtained  only  in  very 
limited  quantities.  There  are  many  localities  where  combustible 
gases  have  long  been  known  to  issue  from  the  earth.  Gas  has 
been  used  in  China  for  centuries,  conveyed  in  bamboo  tubes  from 
fissures  in  salt  mines,  in  excavations  from  1200  to  1600  feet  in 
depth.  Near  the  Caspian  Sea,  in  Asia,  there  are  several  so-called 
eternal  fires  caused  by  gas  issuing  from  the  soil.  In  parts  of  New 
York  it  issues  from  bituminous  limestone  interspersed  among  the 
slates  and  sandstones  of  the  Portage  group ;  but  the  most  prolific 
sources  of  natural  gas  are  in  the  coal  regions  of  western  Pennsyl- 
vania, where  great  wells  are  yielding  almost  unlimited  supplies  of 
this  light-  and  heat-producing  combustible,  and  which,  in  some  of 
the  larger  cities,  is  being  utilized  not  only  for  illuminating  pur- 
poses, but  for  fuel  in  many  of  the  manufacturing  establishments. 

The  chief  supplies  of  illuminating  gas,  however,  are  derived 
from  the  destructive  distillation  of  various  grades  of  bituminous 
coal,  and,  to  a  more  limited  extent,  from  wood,  peat,  resin,  petro- 
leum, oils  and  fats,  and  from  water  and  coke..  As  the  gas  used  in 
the  dental  laboratory  for  the  generation  of  heat  is  the  common 
house  illuminating  gas  obtained  from  coal,  this  variety  only  will 
be  treated  of  in  this  place. 

Bituminous  coals,  such  as  English  cannel  and  boghead  coals, 
Ohio  cannel,  and  the  coking  coals  of  Pennsylvania,  Maryland,  and 
Virginia,  are  commonly  used  in  the  manufacture  of  illuminating 
gas.  When  bituminous  coal  is  heated  to  redness  in  the  presence 
of  air,  it  is  principally  converted  into  gases  which  unite  with  oxy- 
gen ;  but  if  air  is  excluded,  as  when  the  coal  is  confined  in  retorts, 
the  gaseous  products,  unable  to  unite  with  oxygen,  may  be  col- 


30  MECHANICAL   DENTISTRY. 

lected  in  receivers  and  burned  in  tubes.  The  products  of  the 
destructive  distillation  of  bituminous  coal  consist  of  a  great 
number  of  gases,  liquids,  and  solids,  which  may  be  conveniently- 
included  under  the  following  heads,  according  to  an  analysis  by 
Bunsen : 

Coke,    68.93              Olefiant   gas,    0.78 

Tar,    12.23  Sulphuretted   hydrogen,    ..  0.75 

Water,   7.40              Hydrogen,     0.50 

Marsh    gas,    7.04             Ammonia,    0.17 

Carbonic    oxid,    1.13              Nitrogen,     0.03 

Carbonic    acid,     1.07 

The  illuminating  power  of  the  gas  may  be  regarded  as  depend- 
ing principally  upon  the  amount  of  olefiant  gas  (heavy  carburetted 
hydrogen)  which  it  contains,  the  bulk  of  other  gases  being  carriers 
rather  than  light-producers.  The  olefiant  gas  is  separated  by  igni- 
tion into  marsh  gas  (light  carburetted  hydrogen)  and  carbon,  the 
solid  particles  of  which  become  incandescent  and  emit  white  light, 
which  is  observed  in  the  luminous  cone  of  a  gas  flame,  and  which 
has  the  same  constitution  as  that  of  a  candle.  The  luminosity  of 
a  gas  flame  depends  both  upon  the  percentage  of  heavy  hydro- 
carbons it  contains  and  the  amount  of  atmospheric  air  or  oxygen 
mixed  with  it.  With  the  admixture  of  air  or  oxygen,  the  illumin- 
ating power  of  the  gas  is  diminished,  while  there  is  at  the  same 
time  increased  evolution  of  heat.  This  fact  is  of  interest  and  value 
to  the  dentist,  since  it  underlies  the  construction  of  all  the  modern 
forms  of  heating  appliances  made  on  the  principle  of  the  Bunsen 
burner,  which  provides  for  intermingling  currents  of  atmospheric 
air  and  gas.  Oxygen  thus  applied  to  the  gas  jet,  and  combining 
with  the  carbon  at  the  moment  of  ignition,  greatly  augments  the 
heat  of  the  flame,  while  the  latter  becomes  almost  non-luminous. 

Oxyhydrogen  Gas.  —  A  combination  of  nitrous  oxid  and  illu- 
minating gas  has  been  used  of  late  in  the  dental  laboratory  with 
highly  satisfactory  results,  forming  practically  an  oxyhydrogen 
flame  of  great  heating  power.  (See  Dr.  Knapp's  oxyhydrogen 
blowpipe,  page  44.) 


CHAPTER  II. 

APPLIANCES  USED  IN  THE  GENERATION  AND  APPLICATION  OF 
HEAT;  WITH  SOME  OBSERVATIONS  ON   SOLDERING. 

The  modes  of  generating  heat,  and  the  appliances  used  in  its  ap- 
plication to  the  various  mechanical  processes  of  the  dental  labora- 
tory, will  require  more  or  less  detailed  descriptions  of  the  several 
agencies  employed  for  these  purposes.  These  relate  to  Lamps, 
Burners,  Blowpipes,  Supports,  Crucibles,  and  Furnaces.  As  full  a 
description  of  these  several  appliances  will  be  given  as  is  compati- 


FlG.    I. 


ble  with  the  scope  of  the  present  work.  The  agencies  employed 
in  the  generation  and  application  of  heat  alluded  to  under  the  head 
of  lamps,  burners,  supports,  and  blowpipes,  are  such  as  are  used 
chiefly  in  soldering,  one  of  the  most  important  and  not  always  the 
least  difficult  processes  of  the  dental  laboratory,  while  furnaces  are 
largely  used  for  melting  and  refining  purposes,  compounding  body 
and  gum  materials,  baking  porcelain  teeth,  and  in  constructing 
continuous-gum  work.     Heaters  are  adapted  to  a  variety  of  pur- 


32 


MECHANICAL    DENTISTRY. 


Fig. 


poses  requiring  moderate  temperatures,  as  melting  some  of  the 
more  fusible  metals,  warming  water,  heating  plaster  molds  pre- 
paratory to  packing  plastic  substances,  etc. 

Lamps.  —  For  all  the  minor  operations  of  the  laboratory  requir- 
ing the  application  of  moderate  degrees  of  heat  in  the  use  of 
either  the  mouth  or  the  simpler  forms  of  bellows  blowpipe,  an 
ordinary  alcohol  lamp  or  the  gasolene  furnace  described  on  page 
55  will  be  found  serviceable  and  efficient.  When,  however,  gas 
can  be  commanded,  it  is  preferable  to  the  oils  or  alcohol  for  heat- 
producing  purposes,  on  account  of  its  greater  convenience  and 
freedom  from  accident. 

Burners. — The  ordinary  gas  flame  is  unsuitable  for  soldering 
or  other  operations,  by  reason  of  the  carbonaceous  residue  with 
which  it  is  constantly  charged.  This  source  of  uncleanliness  may 
be  gotten  rid  of  by  an  admixture  of  air  with  the  gas  flame.  This 
intermingling  of  gas  and  air  currents  for  the 
purpose  of  augmenting  the  heat  of  the  gas 
flame,  and  of  rendering  it  in  other  respects 
more  suitable  for  general  metallurgic  pur- 
poses, was  first  practised  by  Bunsen,  a  dis- 
tinguished German  chemist,  by  means  of  a 
simple  contrivance  represented  in  Fig.  2. 
All  modern  heat-producing  appliances  usu- 
ally denominated  Bunsen  burners  utilize 
the  same  principle  in  the  generation  of 
heat,  and  differ  only  in  mechanical  con- 
struction from  Bunsen's  original  device. 
A  very  simple  contrivance  embracing  the  principle  of  the  Bun- 
sen burner,  is  shown  in  Fig.  3.  The  gas  is  supplied  through  a 
flexible  rubber  tube  connected  with  the  stem  of  the  burner,  and 
connected  at  the  other  end  with  any  ordinary  gas  burner  conve- 
niently located  in  the  laboratory.  For  soldering  small  pieces, 
and  for  many  other  purposes  requiring  a  ready  and  manageable 
heat,  the  writer  has  used  this  simple  appliance,  with  great  satis- 
faction. It  is  especially  useful  in  "waxing  up"  a  base  plate, 
heating  water,  vulcanizing,  and  other  minor  operations  requiring 
a  moderate  and  easily-graduated  heat. 

To  obtain  a  flame  of  greater  volume  than  is  possible  with  the 
burner  just  described,  one  such  as  shown  in  Fig.  4  is  employed. 


GENERATION    AND   APPLICATION    OF    HEAT. 


33 


This  contrivance  is  especially  adapted  to  drying  and  heating  up 
large  pieces  before  soldering,  and  for  melting  metals  in  consider- 
able quantities. 

Another  heating  apparatus  of  recent  introduction,  designed,  in 

Fig.  3. 


Fig.  4. 


part,  for  soldering  with  the  use  of  blowpipes,  is  represented  in 
Fig.  5.  It  is  called  the  "Perfect  Duplex  Burner,"  and  will  be 
found  very  convenient  for  laboratory  use.     It  is  an  important  ad- 

Fig.  s. 


vance  beyond  the  well-known  revolving  form  of  duplex  burner. 
Both  burners  are  fixed,  and  a  small  jet  is  placed  between  them, 
the  gas  flow  being  governed  by  a  knob,  a  quarter  turn  of  which  to 
the  right  or  left  ignites  either  burner  when  once  the  small  jet  is 

3 


34  MECHANICAL   DENTISTRY. 

lighted.  The  plug  has  a  long  bearing,  and  is  carefully  ground  in 
so  as  to  eliminate  wear  as  far  as  possible.  The  knob  is  not  af- 
fected by  the  heating  up  of  either  burner.  The  apparatus  is  well 
made,  with  every  observed  defect  of  the  old  form  eliminated  and 
every  shortcoming  remedied.  The  old  form  was  good ;  the  new 
is  better,  and  comes  very  close  to  fulfilling  the  intention  of  the  in- 
ventor— to  supply  the  need  of  metal-workers  for  a  perfect  self- 
lighting  soldering  and  Bunsen  burner  combined. 

BLOWPIPES. 

Following  the  description  of  lamps  and  burners  given  in  the 
preceding  pages,  it  would  seem  appropriate  to  consider  next  the 
various  forms  of  blowpipes  used  in  the  application  of  the  heat 
produced  by  means  of  the  appliances  named. 

Various  modifications  in  the  form  of  the  blowpipe  have  been 
introduced  from  time  to  time,  and  are  named  according  to  the 
means  used  to  produce  the  blast,  as — mouth,  bellows,  self-acting, 
or  spirit,  and  the  Gasolene  or  "Oxycarbon"  blowpipe. 

In  addition  to  the  varieties  mentioned,  there  are  others,  used  in 
producing  extreme  degrees  of  heat,  as  the  "oxygen  blowpipe," 
with  which  the  flame  is  blown  with  a  jet  of  oxygen ;  and  another, 
with  which  the  two  gases,  oxygen  and  hydrogen,  are  burned, 
called  the  "oxyhydrogen  blowpipe."  The  latter  is  capable  of 
producing  a  heat  that  immediately  fuses  the  most  refractory  sub- 
stances, as  quartz,  flint,  rock-crystal,  plumbago,  etc.  With  it  gold 
is  volatilized  and  iron  rapidly  consumed  when  placed  in  the 
flame ;  while  platinum,  next  to  iridium  the  most  infusible  of  all 
known  metals,  has  been  melted  in  quantities  exceeding  ioo  ounces 
by  means  of  this  powerful  instrument.  As,  however,  these  blow- 
pipes are,  for  the  most  part,  of  no  special  practical  utility  in  the 
dental  laboratory,  reference  will  be  had  only  to  the  one  recently 
introduced  by  Dr.  Knapp,  of  New  Orleans,  La.  Nor  is  it  deemed 
necessary  to  embrace  descriptions  of  spirit  blowpipes,  as  they 
have  fallen,  of  late  years,  almost  wholly  into  disuse. 

MOUTH    BLOWPIPE. 

This  instrument  has  been  long  in  use,  is  simple  in  its  form  and 
construction,  and,  for  general  use  in  the  application  of  moderate 
degrees    of   heat,    is   both    convenient   and    economical.     Those 


GENERATION    AND    APPLICATION    OF    HEAT. 


35 


accustomed  to  its  use  are  enabled  to  produce  a  continuous  blast 
of  considerable  force,  and  soon  acquire  the  facility  of  regulating 
the  heat  produced  with  equal  if  not  greater  precision  than  can  be 
readily  attained  in  any  other  way. 

The  most  simple  form  of  the  mouth  blowpipe  is  shown  in  Fig. 
6.  It  consists,  usually,  of  a  plain  tube  of  brass,  larger  at  the  end 
applied  to  the  mouth,  and  tapering  gradually  to  a  point  at  its 
other  extremity,  the  latter  being  curved  and  tipped  at  the  point 
with  a  conical-shaped,  raised  margin,  to  protect  it  from  the  action 
of  the  flame ;  the  caliber  of  the  instrument  terminates  here  in  a 
very  small  orifice.  The  point  of  the  instrument,  as  well  as  that 
part  of  it  received  into  the  mouth,  is  sometimes  plated  with  a 
less  oxidizable  metal  than  brass^  as  silver  or  platinum.  The  stem 
is  generally  from  12  to  20  inches  in  length,  and  the  mouth  ex- 
tremity from  y-2.  to  Y\  of  an  inch  in  diameter. 

In  operations  requiring  protracted  blowing,  a  somewhat  dif- 
ferent form  of  the  instrument  will  be  required,  owing  to  the  accu- 

Fig.  6. 


mulation  of  moisture  within  the  tube,  which,  being  forcibly 
expelled  from  the  orifice,  spurts  upon  whatever  is  being  heated 
and  interrupts  the  blast;  also,  on  account  of  the  fatigue,  which 
in  process  of  time  renders  the  muscles  of  the  mouth  and  face 
engaged  in  the  act  to  a  great  extent  powerless. 

The  difficulties  mentioned  may  be  obviated,  in  a  great  measure, 
by  applying  the  form  of  blowpipe  represented  in  Fig.  7.  To  the 
mouth  extremity  is  attached  a  circular  concave  flange  or  collar 
which  receives  and  supports  the  lips.  To  the  shaft,  near  its 
curved  extremity,  is  adjusted  either  a  spheric  or  cylindric  chamber 
which  collects  and  retains  the  moisture  as  it  forms  within  the  pipe. 
By  allowing  that  part  of  the  tube  connected  with  the  curved  end  to 
pass  part  way  into  the  chamber,  a  basin  is  formed  at  the  depending 
portion  of  the  latter,  which,  by  collecting  the  fluids,  will  effectually 
prevent  them  from  overflowing  and  passing  into  the  tube  beyond. 


36 


MECHANICAL   DENTISTRY. 


Another  form  of  mouth  blowpipe  is  exhibited  in  Fig-.  8.  It  will 
be  seen  to  be  wholly  unlike  any  mouth  blowpipe  yet  devised,  and 
admits  of  great  latitude  of  movements  in  the  application  of  heat. 
This  form  of  the  mouthpiece  is  especially  adapted  to  continued 
blowing  without  strain  on  the  lips,  while  the  opening  is  well 
under  the  control  of  the  tongue.  The  blowpipe  proper  is  held 
as  a  pencil,  the  chamber  collecting  condensed  moisture  and  pre- 

Fig.  7. 


venting  the  passage  of  heat  up  to  the  end.  The  instrument  can 
be  readily  changed  from  a  cold-  to  a  hot-blast  blowpipe  by  sub- 
stituting the  coil  (b)  for  the  plain  jet  or  tip. 

There  are  other  allied  forms  of  the  mouth  blowpipe,  but  as  they 
are  constructed  more  especially  for  chemical  examinations  or  anal- 
yses, and  as  they  possess  no  advantages  for  dental  purposes,  over 
those  already  mentioned,  a  description  of  them  is  not  necessary. 


Fig.  8. 


Mechanism  Involved  in  the  Act  of  Producing  a  Continuous 
Blast  with  the  Mouth  Blowpipe. — As  a  steady,  continuous  cur- 
rent of  air  from  the  blowpipe  is  preferable  to  the  interrupted  jet 
in  all  those  operations  where  it  is  desired  to  produce  a  steadily 
augmenting  heat,  the  following  remarks  explanatory  of  the 
method  of  producing  it  are  subjoined,  in  the  belief  that  they  will 
render  easier  a  process  not  always  readily  acquired. 


GENERATION    AND    APPLICATION    OF    HEAT. 


37 


"The  tongue  must  be  applied  to  the  roof  of  the  mouth,  so  as  to 
interrupt  the  communication  between  the  passage  of  the  nostrils 
and  the  mouth.  The  operator  now  fills  his  mouth  with  air,  which 
is  to  be  passed  through  the  pipe  by  compressing  the  muscles  of 
the  cheeks,  while  he  breathes  through  the  nostrils  and  uses  the 
palate  as  a  valve.  When  the  mouth  becomes  nearly  empty,  it  is 
replenished  by  the  lungs  in  an  instant,  while  the  tongue  is  mo- 
mentarily withdrawn  from  the  roof  of  the  mouth.  The  stream 
of  air  can  be  continued  for  a  long  time  without  the  least  fatigue 
or  injury  to  the  lungs. 

"The  easier  way  for  the  student  to  accustom  himself  to  the  use 
of  the  blowpipe,  is  first  to  learn  to  fill  the  mouth  with  air,  and 
while  the  lips  are  kept  firmly  closed  to  breathe  freely  through  the 
nostrils.  Having  effected  this  much,  he  may  introduce  the  mouth- 
piece of  the  blowpipe  between  his  lips.  By  inflating  the  cheeks 
and  breathing  through  the  nostrils,  he  will  soon  learn  to  use  the 
instrument  without  the  least  fatigue.  The  air  is  forced  through 
the  tube,  against  the  flame,  by  the  action  of  the  muscles  of  the 
cheeks,  while  he  continues  to  breathe,  without  interruption, 
through  the  nostrils.  Having  become  acquainted  with  this  proc- 
ess, it  only  requires  some  practice  to  produce  a  steady  jet  of  flame. 
A  defect  in  the  nature  of  the  combustible  used,  as  bad  oil,  such  as 
fish  oil,  or  oil  thickened  by  long  standing  or  by  dirt,  dirty  cotton 
wick,  or  an  untrimmed  one,  or  a  dirty  wick-holder,  or  a  want  of 
steadiness  of  the  hand  that  holds  the  blowpipe,  will  prevent  a 
steady  jet  of  flame.  But,  frequently,  the  fault  lies  in  the  orifice  of 
the  jet, as  too  small  a  hole  or  its  partial  stoppage  by  dirt,  which  will 
prevent  a  steadyjet  of  air  and  lead  to  difficulty.  With  a  good  blow- 
pipe, the  air  projects  the  entire  flame,  forming  a  horizontal,  blue 
cone  of  flame, which  converges  to  a  point  at  about  an  inch  from  the 
wick,  with  a  larger,  longer,  and  more  luminous  flame  enveloping 
it,  and  terminating  at  a  point  beyond  that  of  the  blue  flame."  * 

BELLOWS   BLOWPIPE. 

There  are  many  processes  of  the  dental  laboratory  requiring  the 
application  of  a  higher  temperature  than  is  obtainable  with  the 
mouth  blowpipe.     A  more  powerful  and  persistent  air-blast  is 

*  "  The  Practical  Use  of  the  Blowpipe." — Anon. 


38 


MECHANICAL   DENTISTRY. 


readily  produced  by  a  bellows  or  foot-blower,  used  commonly  in 
connection  with  a  burner  of  suitable  form  attached  to  the  common 
gas-jet,  by  means  of  which  the  gas  is  furnished  with  the  oxygen 
required  for  its  combustion  in  a  state  of  intimate  mixture. 

A  simple  and  compact  form  of  bellows  or  foot-blower  is  shown 
in  Fig.  9.  The  pressure  obtainable  with  this  instrument  is  contin- 
uous, equable,  and  completely  under  the  control  of  the  operator, 
but  the  current  may  be  greatly  increased  in  power  after  the  rub- 
ber disk  is  distended  until  forced  against  the  net. 

A  bellows  of  similar  construction,  but  with  the  position  of  the 
blower  reversed,  is  shown  in  Fig.  10.  By  this  arrangement  the 
disk  is  less  liable  to  injury,  while  it  prevents  the  valve  from  pick- 
ing up  dirt  from  the  floor. 


Fig.-  9. 


Fig. 


A  contrivance  essentially  different  in  its  construction  from  the 
ordinary  bellows  employed  to  produce  the  air-jet  is  shown  in  Fig. 
11,  and  is  known  as  the  "Burgess  Mechanical  Blowpipe."  When 
in  use,  the  air  is  drawn  into  a  cylinder  and  condensed  in  an  air- 
chamber,  ready  to  be  used  in  large  or  small  quantities  at  the  will 
of  the  operator,  by  a  rapid  or  slow  movement  of  the  treadle.  A 
pressure  of  from  2  to  12  pounds  is  produced  at  the  will  of  the 
operator,  by  accelerating  the  motion  of  the  foot,  and  can  be. con- 
tinued with  but  little  exertion.  The  machine  weighs  12  pounds, 
and  measures  22  inches  in  height.  The  pump-cylinder  is  2J/2 
inches  in  diameter,  with  three-inch  stroke.  The  internal  mechan- 
ism is  clearly  illustrated  in  Fig.  11,  and  its  simplicity  will  be  at 
once   appreciated.     It  requires   an   occasional   drop   of   oil   upon 


GENERATION    AND    APPLICATION    OF    HEAT. 


39 


the  leather  packing-ring,  and  this,  with  ordinary  care,  will  make 
the  apparatus  last  for  years.  When  operating,  place  the  entire 
foot  upon  the  treadle,  so  that  an  easy  rocking  motion  is  obtained ; 
by  pressing  the  toe  downward,  air  is  drawn  into  the  cylinder,  and 
in  reversing  the  motion  it  is  driven  into  the  air-chamber  above. 
The  pipe-outlet  is  much  smaller  than  in  the  mouth  blowpipe,  to 

Fig.   ii. 


....         ; 


enable  a  pressure  to  be  obtained,  which  is  increased  or  dimin- 
ished by  a  quick  or  slow  motion  of  the  treadle.  The  air-chamber 
is  easily  filled,  and  when  so  a  constant  supply  of  pure  air  is  at  the 
control  of  the  operator. 

The  blowpipes  used  in  connection  with  the  bellows  are  of  vari- 
ous forms.  Fig.  12  represents  one  form  of  apparatus  employed 
in  the  application  of  the  air-blast  to  the  gas-flame. 

A  movable  gas-jet  attached  to  two  short  arms  of  an  ordinary 


4° 


MECHANICAL  DENTISTRY. 


gas-pipe  is  made  to  receive  within  it  the  blowpipe  point  connected 
with  the  rubber  tube,  the  air-tube  terminating  a  little  within  the 
open  mouth  of  the  gas-jet;  it  is  thus  a  tube  within  a  tube,  with  a 
space  between  them  for  the  admission  and  passage  of  gas.  The 
gas,  being  admitted  by  turning  the  tap  connected  with  the  gas- 
pipe,  is  ignited,  when  the  current  of  air  from  the  bellows  will 
strike  the  center  of  the  flame  and  project  it  upon  whatever  is  to  be 
heated.  The  connected  portions  of  the  air-  and  gas-jets  are  so 
attached  to  the  main  pipe  as  to  admit  of  an  upward  and  down- 
ward motion,  while  the  volume  of  gas  and  air  is  readily  gradu- 
ated by  the  stop-cocks  attached  to  the  air-  and  gas-tubes. 

A  bellows  blowpipe,   constructed   on   similar   principles,   but 


Fig.  12. 


Fig.  13. 


Fig.  14. 


admitting  of  greater  latitude  of  movements,  is  exhibited  in  Fig. 
13.  As  will  be  readily  observed,  it  is  capable  of  being  adjusted 
in  any  desired  position.  The  jet-tube  may  be  raised  or  lowered 
to  any  height  and  turned  in  any  direction.  A  touch  will  direct 
the  flame  on  any  point  while  the  blowpipe  stands  in  the  same 
position  on  the  table ;  there  being  no  necessity  for  raising,  lower- 
ing, or  adjusting  work  before  it. 

Macomber's  gas  blowpipe,  Fig.  14,  differs  somewhat  in  construc- 
tion from  the  latter,  its  capability  of  adjustment  being  regulated  by 
a  ball-and-socket  attachment  which  imparts  to  it,  at  the  will  of  the 
operator,  a  latitude  of  movement  or  adjustment  of  the  blowpipe 
point  that  is  practically  without  limit.  The  direction  of  the  point, 
1,  is  regulated  by  the  joint,  3,  and  the  supply  of  gas  controlled  by 


GENERATION    AND    APPLICATION    OF    HEAT. 


41 


the  stop-cock,  2.     The  air  is  supplied  by  the  bellows  through  the 
flexible  tube. 

A  very  convenient,  manageable,  and  effective  instrument  for 
many  purposes  requiring  the  application  of  heat  in  the  dental 
laboratory  is  the  hand  blowpipe  shown  in  Fig.  15.  It  is  capable 
of  producing  very  high  degrees  of  heat,  but  the  intensity  of  the 

Fig.   15. 


latter  may  be  graduated  at  the  will  of  the  operator,  as  the  stop- 
cocks, which  are  both  under  perfect  control  of  the  thumb  of 
the  hand  which  holds  the  blowpipe,  regulate  the  supply  of  gas, 
and  control  the  volume  of  air.  The  air-jet  is  */&  of  an  inch  bore, 
and  requires  a  supply  from  a  bellows. 

Fig.  16. 


Fig.  16  represents  an  improved  pattern  of  the  Fletcher  Automa- 
ton, designed  especially  for  crown-  and  bridge-work.  It  is  made 
of  smaller  tubing  than  the  No.  6  A  or  B  Automaton,  the  end 
being  bent  at  an  angle  to  give  greater  facility  in  directing  the 
flame.  The  adjustable  nozzle  is  screwed  on  and  off,  instead  of 
operating  by  a  slip-joint,  as  in  other  patterns  of  the  automaton 


42  MECHANICAL   DENTISTRY. 

blowpipe.  Its  length  is  increased,  removing  the  hand  further 
from  the  heat.  The  supply  of  gas  and  air  is  controlled  by  a  longi- 
tudinal movement  of  the  tube,  instead  of  a  rotative  one.  A  spring 
opposes  the  movement  of  the  hand,  and  a  slight  variation  of  press- 
ure upon  the  end-piece,  when  it  is  held  as  shown,  is  sufficient  to 
give  either  a  pointed  jet  or  a  full-sized  brush  flame  at  pleasure. 
An  improved  tip  is  used  on  the  air-jet,  and  the  small  blue-pointed 
reducing  flame  is  very  easily  and  perfectly  produced. 

The  gas  passage  does  not  close  entirely,  but  allows  the  passage 
of  enough  gas  to  prevent  the  flame  from  going  out  when  the  blow- 
pipe is  not  in  use.  It  can  be  hung  up  by  the  ring  shown  on  its 
body,  when  it  is  desirable  to  get  it  out  of  the  hand. 

The  several  forms  of  bellows  blowpipe  illustrated  in  these  pages 
are  complete  and  efficient,  and  admirably  adapted  to  the  necessi- 
ties of  the  mechanical  operator.  In  most  instances,  the  jet  may  be 
elevated  or  depressed  at  will,  while  the  force  of  the  air-current 
and  the  volume  of  the  gas-flame  can  as  readily  be  increased  or 
diminished.  The  operator  is  thus  enabled,  with  the  greatest  ease, 
to  produce  a  heat  adapted  to  the  most  delicate  operations,  or  to 
instantly  change  it  to  a  heat  so  intense  that  pure  gold  in  consider- 
able quantities  is  almost  immediately  fused  in  the  flame.  They  are, 
therefore,  well  adapted  to  all  operations  in  the  dental  laboratory. 

THE   GASOLENE   OR   OXYCARBON    BLOWPIPE. 

Where  illuminating  gas  is  not  available,  the  oxycarbon  forge 
or  blowpipe  will  be  found  most  useful.  It  gives  a  high,  steady, 
smokeless,  and  nearly  odorless  blast,  and  at  the  same  time  does 
not  require  either  the  bellows  attachment  or  lung  power.  It  is 
less  expensive  than  gas  or  alcohol,  is  safe,  portable,  durable,  and 
is  simple  to  control  and  handle.  It  can  be  changed  instantly  from 
an  intense  heat  to  a  feeble  flame,  or  the  reverse.  The  entire  forge 
is  only  about  12  inches  high,  having  a  base  9  inches  in  diameter, 
and  can  be  run  all  day  with  y2  gallon  of  74  °  deodorized  gasolene 
(see  page  55)  without  any  attention,  excepting  a  few  minutes' 
use  with  the  rubber  bulb  to  keep  up  the  necessary  air  pressure. 
This  forge  is  illustrated  in  Figs.  17,  18,  and  19. 

It  can  be  used  for  vulcanizing,  heating  investments,  soldering, 
melting  metals,  annealing  plates,  for  waxing,  or  any  purpose  for 
which  heat  may  be  required  in  the  laboratory. 


GENERATION    AN 


ND    APPLICATION    OF    HEAT. 


43 


Fig.  17- 


Fig.  i  i 


44 


MECHANICAL   DENTISTRY. 


OXYHYDROGEN    BLOWPIPE. 

No  dental  laboratory  appliance  for  heating  purposes  has  ever 
been  devised  that  has  attracted  so  much  attention,  or  elicited  such 
cordial  and  unreserved  praise  by  expert  manipulators,  as  that 
invented  by  Dr.  J.  Rollo  Knapp,  of  New  Orleans,  La.,  and  shown 
in  Fig.  20. 

It  is  described  as  being  to  all  intents  and  purposes  an  oxy- 
hydrogen  blowpipe  divested  of  the  cumbersome  paraphernalia 
usually  accompanying  the  latter,  and  reduced  to  a  practical  size 

Fig.  19. 


and  shape  for  soldering  operations.  It  is  essentially  an  apparatus 
for  securing  the  consumption  of  hydrogen  in  a  highly  oxygenated 
atmosphere,  the  resulting  flame  being  second  in  intensity  only  to 
that  of  the  oxyhydrogen  blowpipe  proper.  It  will  melt  gold  or  its 
alloys  in  quantities  suited  to  its  capacity  almost  instantly,  without 
other  exertion  on  the  part  of  the  operator  than  the  adjustment  of  a 
couple  of  small  levers.  It  is  economical  of  time  and  materials,  and 
not  the  least  notable  of  its  good  qualities  is  its  cleanliness.  Its 
inventor  has  been  accustomed  to  do  all  his  soldering  of  crown- 
and  bridge-work  without  leaving  the  operating  room.  It  can  be 
used  wherever  illuminating  gas  is  available.    Any  of  the  soldering 


GENERATION    AND    APPLICATION    OF    HEAT. 


45 


operations  of  the  laboratory,  from  the  largest  piece  of  bridge- 
work  to  the  most  delicate  joining  of  the  narrowest  bands  or  finest 
wires,  are  accomplished  with  equal  facility.  With  illuminating 
gas  of  good  quality  and  sufficient  pressure,  a  pennyweight  of  20- 
carat  gold  can  be  melted  in  thirty  seconds.  When  the  invest- 
ment is  large,  it  must  first  be  heated  by  other  means. 

The  apparatus  consists  of  the  blowpipe  attachments,  connected 
to  the  yoke  of  a  nitrous  oxid  gas-cylinder,  the  cylinder  being  set 
upright,  and  secured  by  a  thumb-screw  on  one  end  of  an  iron  base 

Fig.  20. 


or  stand,  at  the  other  end  of  which  is  pivoted  a  table,  upon  which 
to  rest  the  work.  The  blowpipe  proper  is  a  continuation  of  the 
outlet  tube  of  the  gas-cylinder.  A  lever-valve,  G,  regulates  the 
supply  of  nitrous  oxid.  Just  beyond  this  valve  is  the  mixing 
chamber  K,  to  which  the  illuminating  gas  is  conducted  from  the 
gas-bracket  by  means  of  rubber  tubing,  entering  the  bottom  of  the 
chamber  through  the  valved  tube,  C.  The  lever,  D,  controls  the 
supply.  The  mixing  chamber  is  provided  with  a  gauze  screen  to 
prevent  the  flame  from  being  drawn  into  the  supply  tubes.    Imme- 


46  MECHANICAL   DENTISTRY. 

diately  beyond  the  mixing  chamber  the  pipe  is  branched  to  afford 
two  flames  of  different  sizes,  E  and  F,  which  can  be  used  inde- 
pendently of  each  other  or  both  together.  The  valve-lever,  L, 
regulates  the  flame  in  both.  For  greater  convenience  in  manipu- 
lation the  pipe-nozzles  are  connected  with  the  branched  pipe  by 
rubber  tubing.  From  the  body  of  the  valve  L  an  arm  extends,  at 
the  end  of  which  is  a  small  scalloped  disc  as  a  holder  for  the 
flame-nozzles  when  not  in  use.  In  the  illustration  one  of  the  noz- 
zles is  shown  in  the  holder,  the  other  being  directed  to  the  re- 
volving table. 

SUPPORTS. 

There  are  many  processes  in  the  dental  laboratory  for  which  it 
is  necessary  to  provide  a  suitable  holder  or  support,  as  in  melting 
small  quantities  of  gold  and  silver,  and  in  all  the  varied  opera- 
tions requiring  the  use  of  solder. 

For  melting  or  soldering  small  pieces,  a  variety  of  simple  de- 
vices, easily  and  economically  constructed,  may  be  used,  among 
which  are  the  following: 

Charcoal,  either  alone  or  combined  with  other  non-conducting 
substances,  is  very  commonly  employed,  and  being  combustible, 
adds  materially  to  the  heat  of  the  blowpipe-flame.  A  convenient 
support  of  this  kind  may  be  made  by  selecting  a  fair-sized  block 
of  compact,  close-grained  charcoal,  derived  from  some  of  the 
hard  woods,  such  as  oak  or  beech,  and  investing  it  in  plaster 

^2  or  ^4  of  an  inch  thick,  one  end  or 
Fig.  2i.  side  being  left  open  and  made  concave,  to 

^r^^^^^^^^%.  receive  whatever  is  being  heated.  Or  a 
fj^k  B  1     plaster  cup,  two  or  three  inches  deep  and 

'v  ^5  P^Jl      three  or  four  inches  in  diameter,  may  be 

■Ifei    ,.,.  ..-■risSfiSffl''      used,  its  interior  being  filled  with  a  mix- 

■K  WB      ture   of  plaster,   sand,  asbestos,   and   pul- 

l|i:''  IIIIIBi^^^        verized    charcoal.      Coke,   encased   in   the 

same  manner  as  charcoal,  may  be  substi- 
tuted for  the  latter,  and  has  the  merit  of  being  more  lasting,  but  in 
all  other  respects  is  inferior  for  the  purpose.  Supports  for  the  uses 
under  consideration  are  also  sometimes  made  of  pumice-stone. 

Manufactured  supports,  composed  of  asbestos  and  carbon,  very 
convenient  and  durable,  may  be  obtained  at  the  dental  depots. 
Fig.  21  represents  a  carbon  block  designed  for  melting  and  solder- 


GENERATION    AND    APPLICATION    OF    HEAT. 


47 


ing,  while  Fig.  22  shows  an  asbestos  block  manufactured  for  the 
same  purpose. 

For  soldering  purposes  exclusively,  especially  in  uniting  teeth 
to  a  metallic  base,  either  of  the  following  means  of  support  for  the 


Fig.  22. 


invested  piece  will  be  suitable :  A  simple  holder,  which  the  opera- 
tor himself  can  easily  construct,  may  be  made  of  a  circular  or 
semi-elliptic  piece  of  heavy  sheet  iron,  the  margin  of  which  is  ser- 
rated and  turned  at  right  angles,  forming  a  cup.  To  the  under 
side  and  center  of  this  an  iron  rod,  10  or  12  inches  long,  may  be 

Fig.  23. 


permanently  riveted,  or  it  may  be  made  to  revolve  on  the  handle, 
so  that  the  heat  may  be  thrown  directly  upon  any  particular  part 
of  the  piece  to  be  soldered  without  disturbing  the  latter. 

A  small  hand  furnace  (Fig.  23)  is  sometimes  used,  and  will  be 


48 


MECHANICAL   DENTISTRY. 


found  a  very  convenient  and  useful  apparatus,  not  only  for  solder- 
ing, but  for  preparatory  heating.  It  consists  of  a  funnel-shaped 
receptacle  made  of  sheet  iron,  with  a  light  grate  or  perforated 
plate  of  the  same  material  adjusted  near  the  bottom,  and  an  open- 
ing on  one  side,  underneath  the  grate,  for  the  admission  of  air. 
The  upper  part  of  the  holder  is  surmounted  by  a  cone-shaped  top, 
which  may  be  readily  removed  by  a  handle  attached  to  it,  while 
to  the  bottom  of  the  furnace  is  attached  an  iron  rod,  five  or  six 
inches  long  and  terminating  in  a  wooden  handle.  The  piece  to  be 
soldered  is  placed  inside  on  a  bed  of  charcoal,  the  top  adjusted 
to  its  place,  and  the  fuel  ignited ;  when  the  case  is  sufficiently 

Fig.  24. 


heated,  the  top  may  be  lifted  off,  and  the  piece  remaining  in  the 
furnace  soldered  with  the  blowpipe  in  the  usual  manner,  the  fur- 
nace thus  serving  the  purpose  of  a  holder. 

The  Melotte  Clamp  or  Support. — A  very  simple  and  conve- 
nient clamp  or  support,  devised  by  Dr.  George  W.  Melotte,  of 
Ithaca,  N.  Y.,  is  shown  in  Fig.  24  and  is  especially  designed  for 
crown-  and  bridge-work. 

It  is  the  design  of  this  invention  to  provide  means  for  holding 
gold  crown  collars  and  their  caps  so  that  without  change  of  size 
or  shape  their  closed  joints  can  be  neatly  soldered.  Fig.  24  ex- 
hibits a  collar  thus  held.     A  slight  pressure  suffices,  and  this  is 


GENERATION    AND    APPLICATION    OF    HEAT. 


49 


effected  by  pushing  the  jaw  shank  into  the  handle,  which  by  its 
spur  is  then  fixed  in  a  piece  of  charcoal  or  on  the  bench ;  the  jaws 
turn  in  the  handle  to  bring  the  joint  into  position,  when  the  left 
hand  is  set  free  to  manipulate  the  solder  while  the  blowpipe  is 
directed  by  the  right  hand  as  usual. 


FURNACES. 

It  would  be  inconsistent  with  the  design  of  the  present  work 
to  introduce  a  description  of  any  form  of  furnace  other  than  those 
of  practical  use  to  the  dentist.    Many  of  those  used  in  the  arts,  or 

Fig.  25. 


for  chemical  and  pharmaceutical  purposes,  embrace  almost  end- 
less varieties,  and  have  no  special  adaptation  to  the  uses  required 
of  them  in  the  dental  laboratory. 

Draft  or  Wind  Furnace. — A  very  convenient,  portable,  and 
economical  furnace  may  be  made  of  sheet  iron,  of  any  desired 
shape  or  dimensions,  though  usually  of  small  size  and  cylindric 
in  form.  A  light  grate,  or  heavy  piece  of  sheet  iron,  perforated 
with  holes,  to  admit  of  the  passage  of  air,  should  be  adjusted  near 
4 


5o 


MECHANICAL   DENTISTRY. 


the  bottom,  while  above  and  below  the  grate  are  two  openings, 
the  lower  one  communicating  with  the  ash-pit,  and  the  upper  one 
for  the  introduction  of  fuel  and  substances  to  be  heated.  By  sur- 
mounting this  simple  apparatus  with  a  pipe,  or  connecting  it  with 


Fig.  26. 


the  flue  of  a  chimney,  it  will  be  found  efficient  in  many  of  the 
minor  operations  of  the  shop,  as  melting  metals,  heating  pieces 
preparatory  to  soldering,  annealing,  etc. 

A  more  durable  and  serviceable  draft-furnace,  however,  may  be 


GENERATION    AND    APPLICATION    OF    HEAT. 


51 


Fig.  27. 


built  of  masonry,  a  convenient  form  of  which  is  represented  in 
Fig.  25.  The  construction  of  this  stationary  fixture  is  so  plainly 
exhibited  in  the  cut  that  any  extended  description  of  it  seems 
unnecessary.  The  upper  holes  represent  the  entrance  to  the  fire 
chambers,  which  are  distinct  from  each  other ;  the  lower  ones 
communicate  with  the  ash-pit,  which  is  common  to  both  cham- 
bers. Two  fire  apartments  are  here  shown,  one  for  melting  and 
re-fining  the  more  precious  metals,  heating  up  for  soldering,  etc., 
the  other  being  used  exclusively  for  fusing  the  baser  metals,  as 
zinc,  antimony,  lead,  etc.  These  furnaces  are  sometimes  con- 
structed with  a  single  fire-chamber,  but  the  one  exhibited  is  in 
every  way  preferable. 

Baking  Furnace. — The  chief  purposes  to  which  these  furnaces 
are  applied  are  the  manufacture  of  por- 
celain teeth,  single  and  in  sectional  blocks, 
the  preparation  of  silicious  compounds, 
and  the  construction  of  what  is  known  as 
"continuous-gum  work."  An  excellent 
form  of  furnace  is  shown  in  Fig.  26,  which 
is  made  after  the  description  of  Dr.  L.  P. 
Haskell,  who  says  of  it:  "If  you  wish  to 
shut  the  heat  out  of  the  room,  have  a  wire 
frame  made,  over  sides  and  top,  and  sit- 
ting against  the  chimney  with  a  movable 
front,  and  holes  corresponding  with  the 
furnace  openings,  and  cover  with  asbestos 
felt."  This  is  shown  complete  in  the  il- 
lustration. 

A  furnace  especially  designed  and  in- 
troduced for  continuous-gum  work,  is  exhibited  in  Fig.  27.  The 
fire-pit  below  the  muffle  is  of  more  than  usual  capacity,  insuring, 
it  is  claimed,  perfect  results  at  each  baking.  The  part  which  is 
subjected  to  the  greatest  heat  is  free  from  angles  and  incased  with 
sheet  iron,  rendering  it  less  liable  to  crack  from  long  use.  The 
fire  or  ashes  may  be  withdrawn  by  removing  the  two  projecting 
grate-bars.     It  is  24  inches  high  and  12*4  inches  in  diameter. 

As  the  purposes,  heretofore  stated,  for  which  these  several  fur- 
naces are  designed  require  a  steady,  intense,  and  persistent  heat, 
the  fuels  commonly  used,  as  fulfilling  most  perfectly  these  indi- 


52  MECHANICAL   DENTISTRY. 

cations,  are  coke,  or  a  mixture  of  charcoal  and  coke,  and  anthra- 
cite, preference  being  given,  by  many,  to  the  latter. 

It  will  be  observed  that,  in  connection  with  the  several  kinds  of 
furnaces  heretofore  mentioned,  heat  is  generated  by  the  use  of 
solid  fuels.  Within  the  past  few  years,  baking-  or  muffle-furnaces 
have  been  constructed  with  reference  to  their  special  adaptability 
to  the  use  of  gas  in  combination  with  the  air-blast.  While  these 
later  devices  commend  themselves  on  the  score  of  their  greater 
convenience  and  economy  of  time  in  firing,  and  their  freedom  from 
the  dirt  and  smoke  attending  the  use  of  solid  fuels,  their  successful 
application  to  the  special  uses  for  which  they  are  mainly  designed, 
has  been  attended  with  difficulties  which  have  heretofore  been 
adverse  to  their  general  adoption  by  the  profession,  and  which  it 
has  been  the  aim  of  inventors  to  overcome.  This  has  been  meas- 
urably accomplished,  and  the  successes  so  far  attained  give  fair 
promise  of  a  complete  revolution  in  the  modes  of  applying  heat  in 
all  operations  concerned  in  the  fabrication  of  the  various  forms  of 
dental  porcelain.  The  chief  obstacle  to  the  successful  use  of  gas 
in  connection  with  the  air-blast  in  the  processes  relating  to  the 
manufacture  of  porcelain  teeth,  gum-enamels,  continuous-gum 
work,  etc.,  is  in  the  increased  liability  t©  so-called  "gasing,"  or  the 
formation  of  bubbles,  due  to  absorption  and  elimination  of  gas  that 
finds  its  way  into  the  muffle  during  the  process  of  baking.  The 
manner  in  which  this  accident  occurs  is  thus  accounted  for  in  a 
communication  to  the  author  from  Dr.  C.  H.  Land,  of  Detroit, 
Michigan.  Alluding  to  the  kind  of  furnaces  under  consideration, 
the  writer  says : 

"To  be  able  to  fuse  the  body  and  enamel  of  which  artificial 
teeth  are  composed  in  an  easy  and  convenient  manner  is  a  thing 
the  profession  has  studiously  sought  after,  realizing  that,  when 
properly  accomplished,  the  means  to  elevate  prosthetic  dentistry 
from  an  ordinary  mechanical  enterprise  to  one  of  true  art,  would 
be  at  hand.  The  mere  construction  of  a  furnace  after  the  usual 
modes  has  been  simple  enough,  and  the  question  of  securing  the 
necessary  degree  of  heat  was  long  ago  accomplished.  However, 
the  ideal  furnace  demanded  much  more.  It  must  possess  not  only 
the  capacity  of  a  coal  or  coke  fire,  but  also  accomplish  the  work 
in  less  time,  and  require  but  the  minimum  amount  of  exertion  to 
operate  it.  Of  the  many  attempts  to  produce  such,  nearly  all 
have  failed,  owing  to  technicalities  that  were  not  well  understood. 


GENERATION    AND    APPLICATION    OF    HEAT. 


53 


Fig.  zi 


"After  many  experiments,  and  their  accompanying  failures,  it 
has  been  demonstrated  that  to  heat  an  eight-inch  muffle,  3^2 
by  25/2  inches  in  diameter,  to  over  28000  F.,  represents  about 
a  one-man  power  equivalent  to  the  exertion  of  running  the 
ordinary  foot-lathe  or  the  No.  9  bellows,  as  manufactured  by  the 
Buffalo  Dental  Manufacturing  Company,  which  gives  a  working 
pressure  of  iy2  pounds  to  the  square  inch,  and  corresponds 
exactly  to  the  required  amount  of  air  pressure  and  volume  neces- 
sary to  heat  an  eight-inch  muffle  to  28000  F.  Therefore,  to 
make  a  furnace  larger  would 
require  too  much  power,  and 
one  smaller  would  not  do 
for  large  pieces  of  work.  In 
the  production  of  a  suitable 
furnace,  the  whole  working 
apparatus  must  be  as  nearly 
air-tight  as  possible,  the  sup- 
ply of  gas  and  air  must  be 
easily  controlled  and  well  bal- 
anced, with  the  least  amount 
of  friction  in  the  passage 
through  the  pipes.  These, 
with  many  minor  details,  form 
the  basis  of  a  practical  gas- 
furnace. 

"GASING  THE  BODY  AND  ENAMEL 

"The  most  serious  trouble 
with  all  gas-furnaces  has  been 
the  extreme  liability  of  injur- 
ing the  body  and  enamel  by  what  has  been  commonly  called  'gas- 
ing.'  The  accompanying  illustration,  Fig.  28,  will  make  the  phi- 
losophy of  combustion  more  clear,  and  give  the  reasons  why  teeth 
are  injured.  A  represents  the  burner;  BBB,  fire-brick  lining; 
C  C  C,  combustion  chamber;  D,  interior  of  muffle.  The  arrows 
indicate  the  direction  of  the  blast.  The  space  in  the  combustion 
chamber  between  the  lines  E  E  is  where  carbon  monoxid  is 
formed,  a  gas  containing  one  equivalent  less  of  oxygen  than  car- 
bon dioxid,  simply  an  imperfect  state  of  combustion.    It  is  this  gas 


54 


MECHANICAL   DENTISTRY. 


that  injures  the  body  and  enamel.  By  reference  to  the  illustra- 
tion, it  will  be  seen  that  the  little  arrows  are  made  to  appear  pass- 
ing through  the  pores  of  the  muffle,  and  as  the  direction  of  the 
blast  from  the  burner  A  is  directly  against  the  bottom  of  the 
muffle,  with  a  pressure  of  one  pound  to  the  square  inch,  a  portion 
of  the  carbon  monoxid  is  extremely  liable  to  be  forced  through  its 
pores,  and  will  be  taken  up  with  the  body  during  the  first  and  sec- 
ond biscuiting,  here  to  remain  until  the  enameling  process,  and  as 
this  takes  a  much  higher  degree  of  heat,  it  causes  the  gas  to  be 
eliminated,  as  shown  in  the  numerous  small  bubbles  on  the  sur- 
face. The  space  between  the  lines  E  E,  and  within  the  combus- 
tion chamber  C  C  C,  should  be  known  as  the  first  stage  of  com- 
bustion, where  a  certain  portion  of  carbon  monoxid  is  always 
present,  and  the  space  above  the  line  F,  within  the  chamber  C, 
should  be  known  as  the  second  stage,  which  is  perfect  combustion. 
In  the  first  stage  of  combustion  one  equivalent  of  oxygen  from  the 
atmosphere  unites  with  the  hydrocarbon  to  form  carbon  monoxid ; 
in  the  second  stage,  two,  or  perhaps. three,  unite  to  form  carbon 
dioxid,  or  carbonic  acid.  Perfect  combustion  is  always  at  the 
extreme  point  of  the  blowpipe,  as  shown  in  the  illustration. 

"The  attempt,  therefore,  should  be  to  place  the  muffle  as  nearly 
as  possible  in  the  center  of  perfect  combustion.  As  carbon  mon- 
oxid is  not  consumed  short  of  a  temperature  of  over  22000  F.,  the 
teeth  should  be  kept  in  front  of  the  muffle  until  it  approaches  a 
white  heat.  Starting  from  a  cold  muffle  this  will  take  about 
twelve  minutes,  and  they  should  be  gradually  carried  to  the  ex- 
treme end.  At  a  high  temperature,  there  is  very  little  danger  of 
gasing,  unless  a  greater  quantity  of  gas  is  supplied  than  the  fur- 
nace is  capable  of  burning.  Having  constructed  a  furnace,  and 
being  familiar  with  many  other  details  that  provided  a  means  to 
overcome  all  the  apparent  difficulties,  the  success  of  properly  bak- 
ing teeth  seemed  to  be  assured,  until  the  muffle  began  to  crack, 
which  usually  started  in  the  second  or  third  enameling  heat.  This 
let  in  such  a  quantity  of  monoxid  of  carbon  as  to  ruin  the  teeth. 
Here  was  a  difficulty  that  was  overcome  by  forcing  a  quantity  of 
superheated  air  into  the  muffle,  and  backing  all  foul  gases  out. 
This  proved  to  be  a  cure  for  gasing,  but  added  an  excess  of  oxy- 
gen, and  it  was  found  that  this  had  a  tendency  to  bleach  the  gum- 
enamel  to  a  lighter  shade.     The  next  step  was  to  inject  a  pure 


GENERATION    AND   APPLICATION    OF    HEAT.  55 

atmosphere  of  nitrogen  into  the  muffle,  it  being  a  neutral  gas,  not 
uniting  radically  with  anything.  This  was  eminently  successful, 
and  thoroughly  demonstrated  the  fact  that  porcelain  baked  in  an 
atmosphere  of  nitrogen  was  absolutely  perfect,  both  in  color  and 
texture.  It  therefore  gives  me  pleasure  to  be  able  to  announce  to 
the  profession  that  the  baking  of  all  kinds  of  porcelain  with  any 
of  the  hydrocarbons  has  been  brought  within  the  range  of  every 
dental  practitioner,  so  that,  with  a  little  experience  and  knowledge 
of  the  above  facts,  artificial  teeth  can  be  baked,  with  unerring  pre- 
cision, in  a  very  comfortable,  cheap,  and  easy  manner.  By  a  sim- 
ple attachment,  each  furnace  produces  its  own  nitrogen  as  fast  as 
needed,  and  with  recent  improvements  in  the  construction  of 
muffles,  and  the  aid  of  a  small  motor,  the  author  has  been  able  to 
maintain  a  constant  and  uniform  temperature  above  28000  F.,  by 
which  a  slab  of  sectional  gum  teeth  was  completed  every  seven 
minutes,  at  the  will  of  the  operator. 

"  OLEFIANT    GAS    AND    GASOLENE. 

"defiant  gas,  with  which  nearly  all  our  cities  and  towns  are 
supplied,  is  a  compound  of  hydrogen  and  carbon.  Its  symbols  are 
C2H4,  differing  from  gasolene  only  in  its  specific  gravity,  the  com- 
position of  the  latter  being  also  C2H4.  The  former  will  rise  to  the 
top  of  a  building,  while  the  latter  will  fall.  The  former  is  more 
penetrating,  therefore  more  liable  to  gas  the  teeth,  and  hence  requires 
more  care  in  handling.  The  quality  varies  in  different  localities, 
and  sometimes,  owing  to  the  presence  of  ammonia,  it  may  injure 
the  teeth,  or  it  may  be  too  thin.  When  properly  purified,  it  should 
be  a  rich  hydrocarbon.  The  uncertainty  of  its  qualities  is  fre- 
quently the  cause  of  failure.  To  be  successful  with  gas-furnaces, 
it  is  absolutely  necessary  to  have  a  pure  and  rich  hydrocarbon. 
When  the  gas  pressure  is  weak  or  the  quality  is  poor,  a  gasolene 
generator  may  be  attached  to  the  pipe  and  the  current  allowed  to 
pass  through.  This  takes  up  a  large  percentage  of  the  gasolene 
and  provides  a  very  rich  quality  of  gas.  The  87  per  cent,  is  the 
best;  74  per  cent,  is  too  heavy  to  use  without  requiring  heat 
to  vaporize  it.  By  applying  to  the  Combination  Gas  Machine 
Company  a  supply  can  be  had.  When  pure  gasolene  is  used,  it 
is  necessary  to  have  a  generator  so  arranged  that  a  portion  of  the 
air  from  the  bellows  will  pass  through  it.    This  carries  the  vapor 


56  MECHANICAL   DENTISTRY. 

into  the  furnace,  where  it  becomes  mixed  with  the  proper  quantity 
of  air,  and  will  produce  as  good,  if  not  better,  results  than  any 
other  hydrocarbon.  All  kinds  of  crucible  and  muffle  work  can  be 
done  equally  well,  also  soldering  and  brazing  with  the  blowpipe. 
One  gallon  of  gasolene  costs  15  to  20  cents;  this  will  bake  one 
set  of  teeth.  Therefore  it  will  be  seen  that  dentists  living  in  lo- 
calities where  there  is  no  gas  will  not  be  deprived  of  practically 
the  same  advantages  as  their  city  brethren." 

The  Land  Furnace. — The  following  is  a  description  of  a  fur- 
nace, invented  by  Dr.  Land,  designed  especially  to  overcome  the 
trouble  spoken  of  above,  as  well  as  to  provide  other  advantages : 

Size  No.  1  is  especially  adapted  for  all  kinds  of  muffle  work, 
crucible  work,  blowpipe  work,  forging  and  brazing,  assaying,  and 
small  castings  of  iron,  brass,  and  steel.  A  muffle  8  inches  long, 
3^2  inches  wide,  2^2  inches  high,  inside  measurement,  can  be 
heated  to  over  32400  F.  in  twenty-five  minutes,  sufficient  to 
melt  wrought  iron.  Fig.  29  represents  the  furnace  closed  and 
ready  for  muffle  work.  A  A  is  an  iron  pipe,  capable  of  both  a 
sliding  and  a  swinging  motion  (see  L,  Fig.  30),  to- which  the 
door  or  plug  is  securely  attached.  There  is  a  small  hole  in  the 
door,  covered  with  a  piece  of  mica,  through  which  all  operations 
can  be  seen.  Observe  that  the  iron  pipe  is  connected  with  rubber 
tubing,  B,  and  with  pipe  having  an  air-cock,  C,  which  regulates 
the  quantity  of  air  passing  into  the  mouth  of  the  muffle.  It  will 
also  be  noticed  that  the  pipe  passes  over  the  two  holes,  D  D; 
thus  by  the  escaping  flame  the  pipe  is  heated  to  redness  and  pro- 
vides a  superheated  air  before  reaching  the  muffle ;  this  column 
of  air  forced  into  the  muffle  keeps  up  a  counter-pressure  within,  so 
much  greater  than  the  pressure  produced  by  the  blast  within  the 
fire-chamber  that  all  foul  gases  are  prevented  from  entering  the 
muffle  even  though  it  is  cracked ;  thus  the  most  delicate  porcelain 
can  be  baked  without  the  least  danger  of  so-called  gasing.  Also, 
it  will  be  seen  that  by  connecting  the  rubber  pipe  with  retorts  of 
gasometers  any  desired  vapor  or  gas  could  be  forced  into  the 
muffle,  making  the  furnace  invaluable  for  scientific  experiments. 

Fig.  30  illustrates  the  furnace  thrown  open,  being  swung  on 
hinges  at  the  back,  exposing  the  muffle,  E.  The  groove,  P  P,  is 
packed  with  asbestos  fiber,  so  that  when  the  sections  are  brought 
together  the  furnace  will  be  perfectly  air-  and  gas-tight.     The 


GENERATION    AND    APPLICATION    OF    HEAT. 


57 


hooks,  F  F,  are  to  hold  the  upper  section  secure  to  the  lower. 
The  gas  and  air  connections  are  so  arranged  that  the  ordinary- 
blowpipe  can  be  attached,  as  shown  at  G.  When  the  muffle,  E, 
is  removed,  it  exposes  two  burners  and  a  fire-brick  surface  made 
to  fit  the  various  appliances  for  crucible,  ladle,  and  blowpipe  work. 
One  or  both  burners  can  be  operated  in  conjunction  with  the  blow- 

Fig.  29. 


pipe,  G.  The  air-cock,  R,  is  to  provide  a  means  for  shutting  off 
the  air  supply  from  either  burner  when  required.  H  is  the  gas 
supply ;  K,  air-pipe  connecting  with  the  bellows.  Size  of  muffle, 
inside  measurement,  8  inches  long,  ^A  inches  wide,  2^  inches 
high.    With  gasolene  gas  porcelain  teeth  can  be  enameled  in  from 


58 


MECHANICAL   DENTISTRY. 


ten  to  fifteen  minutes ;  with  ordinary  city  gas  in  from  fifteen  to 
twenty-five  minutes,  according  to  quality.  In  thirty  minutes  a 
heat  sufficient  to  destroy  the  muffle  can  be  produced,  which 
indicates  a  temperature  of  over  32400  F.,  much  higher  than  is 
ever  needed  for  any  kind  of  work,  except  the  fusing  of  platinum. 

Fig.  30. 


Three-eighths  of  an  inch  gas-pipe  will  supply  sufficient  gas  and 
can  be  worked  with  the  ordinary  foot-bellows. 

The  Sharpe  Furnace.  —  One  of  the  simplest  and  most  complete 
gas  muffle-furnaces  yet  placed  upon  the  market,  is  that  invented 
by  Dr.  W.  M.  Sharpe,  of  Binghamton,  New  York,  and  is  exhib- 
ited in  Figs.  31  and  32. 


Fig.   31. 


Fig.  32. 


6o 


MECHANICAL   DENTISTRY, 


Gas  Crucible  Furnace  Without  Blast.  —  Fig.  33  represents  a 
small  crucible  furnace  that  will  be  found  very  convenient  for  melt- 
ing and  refining  the  precious  and  more  infusible  metals  employed 
by  the  dentist.  It  takes  crucibles  up  to  2.y2  by  2.]/^  inches  outside, 
and  with  a  three-foot  chimney  will  melt  copper,  gold,  silver,  etc., 
in  about  ten  minutes,  or  cast  iron  in  thirty  minutes  from  the  time 
the  gas  is  lighted. 

The  construction  of  the  burner  used  with  this  furnace  is  illus- 
trated by  the  sectional  diagram,  Fig.  34,  and  is  thus  described : 


Fig.  33. 


Fig.  34. 


"The  gas  enters  a  chamber  at  the  bottom  of  the  burner,  through 
a  device  similar  to  a  Bunsen  burner,  mixing  with  air  as  it  enters, 
and  is  burned  at  the  upper  ends  of  a  series  of  concentric  tubes, 
furnishing  air-spaces  alternately  with  those  supplying  the  mix- 
ture of  gas  and  air.  The  whole  burner  is  constructed  of  iron,  and 
will  be  found  better  able  to  withstand  an  intense  heat,  more  dur- 
able and  quicker  in  its  operation,  than  the  old  pattern  with  gun- 
metal  tubes.  In  case  metal  should  be  spilled  into  the  burner,  it 
can  be  easily  taken  apart  for  its  removal. 

"Each  part  of  the  burner  is  lettered,  and  in  case  of  accident  it 


GENERATION    AND   APPLICATION    OF    HEAT. 


61 


can  be  supplied  at  a  small  expense  by  specifying  the  letter  on  the 
piece  desired. 

"The  burner  in  its  present  shape  is  believed  to  be  the  most  effi- 
cient and  economical  yet  devised  for  furnace  purposes." 

The  following  instructions  in  the  use  of  this  furnace  should  be 
observed : 

"A  chimney  or  stove-pipe,  eight  or  ten  feet  high,  may  be  used 
as  a  fixture,  and  the  draft  partially  stopped  with  a  damper  or 
slide  when  lower  temperatures  are  required,  the  gas  being  turned 
down  in  proportion;  the  guide  for  the  proper  adjustment  being 

that  UNDER  ALL  CIRCUMSTANCES  THE  FLAME  MUST  JUST  COVER  THE 

crucible  or  muffle,  but  not  extend  into  the  chimney  so  as  to 
make  it  red  hot.     When  the  flame  covers  the  crucible  or  muffle  the 

Fig.  35. 


gas  is  doing  its  extreme  duty  under  the  most  favorable  circum- 
stances, without  waste.  Particles  of  flux  should  not  be  allowed  to 
fall  on  the  fire-clay  casing,  where  the  parts  touch  each  other ;  and 
the  power  of  the  furnace  should  not  be  urged  too  far  by  the  use  of 
very  long  chimneys,  as  there  is  danger  of  the  fusion  of  the  fire- 
clay parts  together,  so  that  they  cannot  be  separated.  Fire-clay 
fittings,  as  a  rule,  cannot  be  safely  used  for  temperatures  much 
exceeding  the  fusing-point  of  cast  iron.  Plumbago  fittings  and  cru- 
cibles must  be  heated  slowly  the  first  time  they  are  used.  After  the 
first  time  they  may  be  subjected  instantly  to  the  full  power  of  the 
furnace  without  injury." 

Gas  Crucible  Furnaces  with  Blast. — A  small,  compact,  and 
convenient  crucible  furnace  is  shown  in  Fig.  35.  Of  this  simple 
but  powerful  heating-apparatus,  which  will  be  found  especially 


62  MECHANICAL   DENTISTRY. 

adapted  to  the  necessities  of  the  dental  laboratory,  the  manufac- 
turers* observe : 

"  Owing  to  the  discovery,  by  Mr.  Fletcher,  of  a  singularly  per- 
fect non-conducting  furnace  casing,  we  are  enabled  to  produce  the 
first  really  simple  gas-furnace  ever  constructed.  This  material  is 
only  about  one-sixth  the  weight  of  fire-clay,  and  has  not  one-tenth 
its  conducting  power  for  heat. 

"  The  furnace  consists  of  a  simple  pot — for  holding  the  cruci- 
ble— with  a  lid  and  a  blowpipe,  all  mounted  on  a  suitable  cast- 
iron  base.  As  compared  with  the  ordinary  gas-furnace  it  appears 
almost  a  toy,  owing  to  its  great  simplicity. 

"  The  casing  holds  the  heat  so  perfectly  that  the  most  refrac- 
tory substances  can  be  fused  with  ease,  using  a  common  foot- 
blower.  Half  a  pound  of  cast  iron  requires  from  seven  to  twelve 
minutes  for  perfect  fusion,  the  time  depending  on  the  gas  supply 
and  pressure  of  air  from  the  blower. 

"  The  power  which  can  be  obtained  is  far  beyond  what  is  re- 
quired for  most  purposes,  and  is  limited  only  by  the  fusibility  of 
the  crucible  and  casing. 

"  The  crucible  will  hold  about  ten  ounces  of  gold. 

"  An  ordinary  gas  supply  pipe,  T\  or  ■§-,  will  work  it  efficiently. 
It  requires  a  much  smaller  supply  of  gas  than  any  other  furnace 
known.  About  ten  cubic  feet  per  hour  is  sufficient  for  most  pur- 
poses. 

"  Crucibles  must  not  exceed  2%  by  2  inches.  Any  common 
blowpipe  bellows  will  work  the  furnace  satisfactorily  except  for 
very  high  temperatures  (fusion  of  steel,  etc.),  for  which  a  heavy 
pressure  of  air  is  necessary. 

"  In  adjusting  this  furnace  for  use,  put  the  gauze-nozzle  of  the 
burner  closely  against  the  hole  in  the  side  of  the  casing,  turn  on 
the  gas,  and  light  it  in  the  furnace.  Work  the  bellows  and  then 
put  the  cover  on  the  furnace.  The  air  supply  should  be  such  that 
a  flame  about  two  inches  long  will  play  out  of  the  hole  in  the 
cover,  and  it  may  be  adjusted  by  turning  the  thumb-screw  on  the 
side  of  burner.  The  amount  of  air  and  gas  used  by  this  burner  is 
very  small.  Care  should  be  taken  that  the  right  proportion  of 
each  should  be  used.  A  very  light  but  steady  blast  of  air  will  give 
the  best  results. 

*  Buffalo  Dental  Manufacturing  Company. 


GENERATION    AND    APPLICATION    OF    HEAT.  63 

"A  modified  pattern  of  the  foregoing  furnace  (Fig.  36)  has 
been  designed,  retaining  all  the  peculiar  advantages  of  the  one 
just  described,  but  burning  refined  petroleum  instead  of  gas  as 
fuel,  and  is  claimed  to  be  equally  as  efficient  as  the  gas-furnace. 

"The  burner  of  this  "furnace  is  constructed  upon  the  principle 
of  an  atomizer ;  and  this,  of  course,  dispenses  with  a  wick.  This 
method  has  proven  the  most  efficient  of  any  that  has  been  experi- 
mented with. 

"  The  recent  improvements  consist  in  a  device  for  regulating 
the  supply  of  oil,  which  is  operated  by  the  milled  nut  (marked  A) 
shown  on  top  of  the  reservoir  in  the  cut,  and  the  addition  of  an 
annular  jet  of  air,  which  is  regulated  by  turning  the  sleeve 
(marked  B)." 

This  is  an  approved  crucible  furnace,  and  is  known  as  Fletch- 
er's injector  gas-furnace,  the  construction  of  this  apparatus  being 

Fig.  36. 


upon  the  principle  of  the  injector  furnace,  and  it  is  claimed  that 
its  power  and  speed  of  working  are  practically  without  limit, 
depending  only  upon  the  gas  and  air  supply.  It  is  very  simple 
in  construction,  and  consists  of  two  parts,  an  upper  portion,  which 
forms  the  cover,  and  a  lower  part,  which  holds  the  crucible  while 
in  operation  (see  Fig.  36). 

A  very  useful  and  almost  indispensable  heating-apparatus  in 
the  dental  laboratory,  suitable  for  drying,  boiling,  melting  metals 
requiring  a  moderate  temperature,  as  zinc,  tin,  lead,  etc.,  heating 
flasks  preparatory  to  packing  with  rubber,  and  a  variety  of  other 
purposes,  is  exhibited  in  Fig.  37. 

The  burner,  consisting,  as  will  be  seen,  of  a  circular  perforated 
gas-tube  with  a  central  air-jet,  gives  a  complete  range  of  tempera- 


64 


MECHANICAL   DENTISTRY. 


ture,  from  a  gentle  current  of  warm  air  to  a  clear  red  heat,  and  is 
so  perfectly  tinder  control  that  a  common  glass  bottle  may  be 
placed  on  the  tripod  and  heated  to  any  required  temperature  with- 
out the  slightest  risk  of  fracture.  For  very  low  temperatures  the 
ring  must  be  lighted  through  the  opening  B.  This  gives  a  steady 
current  of  heated  air  through  the  gauze  above.  For  boiling,  melt- 
ing, etc.,  the  light  must  be  applied  on  the  surface  of  the  gauze, 
thereby  providing  a  large  body  of  blue  flame,  which  can  be  urged 
by  the  blastpipe  C.  This  is  one  of  the  most  generally  useful 
burners,  and  stands  hard,  dirty  work  without  injury.  The  gauze, 
if  choked  up  with  dirt,  can  be  replaced  in  a  few  seconds. 

An  equally  convenient  heater  for  many  purposes  requiring  a 
diminished  temperature,  as  compared  with  the  air-blast  heater 


Fig.  37- 


Fig.  38. 


MS*-- ^ =: 


just  described,  is  exhibited  in  Fig.  38.  A  gentle  current  of  air 
passes  through  side  openings  in  the  end  of  the  injecting  tube, 
mingling  with  the  gas  supplied  through  a  rubber  tube  attached  to 
an  ordinary  gas-burner. 

An  admirably  contrived  ladle-furnace,  designed  by  Dr.  Fletcher, 
is  shown  in  Fig.  39.  This  simple  contrivance,  provided  with  a 
heating  apparatus  similar  to  the  burner  last  described,  is  espe- 
cially well  adapted  for  melting  any  of  the  several  metals  usually 
employed  for  dies  and  counter-dies,  as  zinc,  tin,  lead,  Babbitt 
metal,  etc.  The  burner  can  be  removed  from  the  casing  and  used 
for  other  purposes  if  desired.  A  cast-iron  ladle  of  suitable  form, 
with  a  detachable  handle,  which  can  be  removed  during  the  proc- 
ess of  melting,  is  also  illustrated. 


PRINCIPLES    OF   SOLDERING. 


65 


CRUCIBLES. 

Crucibles  are  small,  conical-shaped  vessels  used  by  the  dentist 
principally  for  the  purpose  of  melting  and  refining  metals  used 
for  plates,  compounding  metallic  alloys,  preparing  and  compound- 
ing the  various  ingredients  employed  in  the  manufacture  of 
porcelain  teeth,  continuous-gum  work,  etc.  They  combine  in  a 
high  degree  the  properties  of  infusibility,  exemption  from  the 
attack  of  substances  fused  in  them,  the  power  of  resisting  sudden 
alternations  of  temperature  and  impermeability  to  fluids  and 
gases.  The  Hessian  crucibles,  which  are  in  most  common  use 
among  dentists,  are  composed  of  silica,  alumina,  and  oxid  of  iron. 


Fig.  39. 


Plumbago  crucibles  are  also  made  from  special  patterns,  and  ex- 
pressly designed  for  Fletcher's  furnaces. 

To  avoid  a  possible  loss  of  fused  metals,  which  may  occur  in 
consequence  of  some  imperfection  in  the  crucible,  a  test  should 
be  made  by  placing  in  it  a  small  quantity  of  borax  and  then  sub- 
jecting it  to  a  high  heat.  If  imperfect,  the  borax,  rendered  semi- 
fluid by  the  heat,  will  pass  through  the  substance  of  the  crucible 
and  glaze  the  surface  on  the  outside. 


PRINCIPLES  OF  SOLDERING. 


Successful  soldering  is  dependent  upon  several  conditions,  a 
disregard  of  any  one  of  which  may  mean  much  difficulty,  or  a 
complete  failure.     By  the  close  observance  of  these  conditions 


66  MECHANICAL   DENTISTRY. 

the  difficulties  experienced  in  soldering-  (especially  by  students) 
may  be  reduced  to  a  minimum,  in  fact  the  operation  becomes  very 
simple.    These  conditions  are  : 

First,  contact  of  the  two  surfaces  to  be  united.  If,  for  instance, 
the  ends  of  a  piece  of  plate  are  to  be  united,  as  in  the  formation  of 
a  band  or  ferrule,  they  must  be  so  shaped  as  to  be  in  close  appo- 
sition at  every  point,  as  solder  will  not  bridge  a  space.  Or,  if  it 
be  the  soldering  of  an  artificial  denture,  the  backings  must  be  in 
contact  with  the  plate  to  which  they  are  to  be  united.  In  other 
words,  the  continuity  of  the  metal  must  be  complete  at  the  points 
where  it  is  desirous  to  have  the  solder  flow. 

Second,  cleanliness  of  the  surfaces  over  which  the  solder  is  to 
flow.  That  cleanliness  in  soldering  operations  should  be  observed, 
is  quite  as  necessary  as  that  the  surfaces  to  be  united  should  be  in 
perfect  contact.  The  purity  of  gold  or  silver  is  usually  reduced 
by  alloying  with  copper,  which  readily  oxidizes  when  the  metal  is 
heated  to  redness.  This  oxidation  can  be  readily  removed  by 
immersing  the  piece,  when  practicable,  in  dilute  sulphuric  acid, 
slightly  heated ;  or  a  strong  solution  of  alum  may  be  used — its 
solvent  properties,  however,  are  not  developed  until  brought  to  the 
boiling-point,  2120  F.  Borax  is  also  employed  for  this  purpose; 
it  accomplishes  the  same  result  by  dissolving  the  oxid  from  the 
surface  of  the  metal  at  the  points  where  applied,  and  at  the  same 
time  protects  it  from  further  oxidation.  A  good  practice  is  to 
coat  the  surfaces  to  be  soldered,  before  the  heat  is  first  applied. 

Third,  the  proper  amount  and  application  of  heat.  Where  arti- 
ficial teeth  are  to  be  soldered  the  heating  process,  as  well  as  the 
cooling,  should  be  gradual.  The  greater  the  amount  of  invest- 
ment material,  the  greater  the  amount  of  heat  required  to  bring 
the  piece  to  be  soldered  to  a  uniform  temperature.  It  naturally 
follows  that  the  thickest  part  of  the  investment  must  receive  the 
greatest  volume  of  heat.  Solder  always  flows  toward  the  hottest 
point;  this  tendency  enables  us  to  direct  its  course  under  the 
blowpipe,  by  keeping  the  parts  to  be  soldered  at  a  higher  tem- 
perature than  the  solder  itself.  On  the  other  hand,  if  the  heat  is 
directed  upon  the  solder,  so  that  it  reaches  its  fusing-point  before 
the  parts  upon  which  it  is  placed  are  equally  hot  or  hotter,  it  rolls 
up  into  a  ball,  a  very  troublesome  feature  to  the  majority  of  stu- 
dents.    A  large  flame  from  the  blowpipe  should  only  be  employed 


PRINCIPLES  OF  SOLDERING.  67 

in  "  heating  up  "  the  case,  not  for  the  soldering-  process.  If  these 
three  stages  have  been  carefully  observed,  it  will  be  found  that 
with  a  small  pointed  flame  directed  upon  the  solder  and  the  parts 
to  be  united,  the  solder  will  flow  quickly  and  leave  a  smooth,  even 
surface  at  the  completion  of  the  operation. 


CHAPTER  III. 

METALS  EMPLOYED  IN  DENTAL  LABORATORY  OPERATIONS. 

GOLD. 

Au  (Aurum). 

Gold  has  been  known  from  a  period  of  great  antiquity,  having, 
according  to  the  writings  of  Moses,  been  wrought  into  articles  of 
jewelry  more  than  three  thousand  years  ago.  As  a  base  or  sup- 
port for  artificial  dentures,  it  has  entirely  superseded  the  use  of 
the  various  animal  substances  formerly  employed,  and,  by  the 
mass  of  practitioners  at  the  present  time,  it  continues  to  be  the 
most  highly  esteemed  metal  for  the  purpose  mentioned,  notwith- 
standing the  more  recent  introduction  of  processes  in  which,  as 
a  base,  this  metal  is  wholly  discarded. 

Gold  is  found  in  nature  chiefly  in  the  metallic  state,  and  occurs 
either  crystallized  in  the  cube  and  its  allied  forms,  or  in  threads  of 
various  sizes,  twisted  and  interlaced  into  a  chain  of  minute  octa- 
hedral crystals ;  also  in  spangles  or  roundish  grains.  These  lat- 
ter, when  they  occur  of  a  certain  magnitude,  are  called  pepitas, 
some  specimens  of  which  have  been  obtained  of  great  size.  In 
1810  a  mass  of  alluvial  gold  weighing  28  pounds  was  found  in  the 
gravel-pits  of  the  creeks  of  Rockhole,  in  North  Carolina.  A  lump 
of  gold  ore  weighing  three  cwt.  was  forwarded  from  Chili,  South 
America,  as  a  contribution  to  the  World's  Exhibition  in  London. 
New  Granada,  California,  Russia,  and  Australia  have  each  pro- 
duced pepitas,  or  masses  of  gold  weighing  respectively  27^,  28, 
70,  and  106  pounds.  As  it  occurs  in  nature,  gold  is  never  quite 
pure,  being  generally  associated  with  silver,  though  sometimes  it 
contains  small  quantities  of  platinum,  iridium,  or  palladium. 

Geological  Situations. — The  crystalline  primitive  rocks,  the 
compact  transition  rocks,  the  trachytic  and  trap  rocks,  and  allu- 
vial grounds  are  the  formations  in  which  gold  occurs.  Unlike 
many  other  metals,  it  is  never  in  such  large  quantities  as  to  con- 
stitute veins  by  itself,   but  is  either  disseminated  through   the 

68 


METALS   EMPLOYED  IN   DENTAL   LABORATORY   OPERATIONS.  69 

rocky  masses,  or  spread  out  in  thin  plates  or  grains  on  their  sur- 
face, or  confined  in  their  cavities  in  the  shape  of  filaments  or 
crystallized  twigs.  The  minerals  composing  the  veins  are  either 
quartz,  calcspar,  or  sulphate  of  baryta.  The  ores  associated  with 
the  gold  in  these  veins  are  principally  iron,  copper,  arsenical 
pyrites,  galena,  and  blende.  The  most  abundant  sources  of  gold, 
however,  are  in  alluvial  grounds,  where  it  is  found  distributed  in 
the  form  of  spangles  in  the  sands  of  certain  plains  and  rivers, 
especially  at  their  reentering  angles,  at  the  season  of  low  water 
and  after  storms  and  temporary  floods.  Sufficient  reasons  have 
been  advanced  in  support  of  the  belief  that  gold  found  in  alluvial 
situations  belongs  to  the  grounds  traversed  by  these  rivers,  in- 
stead of  being  washed,  as  was  formerly  supposed,  from  the  moun- 
tains in  which  their  waters  have  their  origin. 

Geographical  Distribution. — The  European  mines  more  par- 
ticularly distinguished  for  their  richness  are  in  Hungary  and 
Transylvania ;  it  also  occurs,  but  more  sparingly,  in  Ireland, 
Sweden,  Siberia,  Germany,  Russia,  Spain.  In  Asia  and  Africa,  the 
mines  which  yield  most  abundantly  are  situated  in  the  southern 
portion  of  these  continents.  From  the  latter,  the  ancients  derived 
the  greater  portion  of  their  gold.  Several  of  the  South  American 
provinces  yield  this  metal  in  considerable  quantities.  Washings 
are  also  common  in  several  States  of  the  Union,  but  California 
stands  unrivaled,  except  by  Australia,  in  the  immense  productive- 
ness of  its  mines,  and  its  resources  in  respect  to  this  rare  and 
valuable  metal  are  reckoned  inexhaustible. 

Properties  of  Gold.  —  Pure  gold  is  distinguished  from  all  other 
metals  by  its  brilliant  orange-red  or  yellow  color,  being  the  only 
simple  metal  that  possesses  this  complexion.  It  is  susceptible  to 
a  high  polish,  but  is  inferior  in  brilliancy  to  steel,  silver,  or  mer- 
cury. Its  specific  gravity  varies  somewhat,  according  as  it  is 
fused  or  hammered ;  the  former  having  a  density  of  19.26,  the 
latter  ranging  from  19.04  to  19.65.  It  is  only  excelled  in  density, 
therefore,  by  platinum,  the  specific  gravity  of  which  is  21.25. 

Gold  surpasses  all  other  metals  in  malleability.  The  average 
thickness  of  ordinary  gold-leaf  is  2T2V00"  °^  an  incn>  Dut  the 
ultimate  degree  of  attenuation  to  which  pure  gold  is  susceptible 
exceeds  considerably  this  estimate.  It  is  also  distinguished  for 
its  ductility.     A  single  grain  of  gold  may  be  drawn  into  wire  50a 


7o 


MECHANICAL   DENTISTRY. 


feet  in  length,  while  an  ounce  may  be  made  to  extend  1300  miles. 
It  is  somewhat  softer  than  silver,  and  possesses  great  tenacity, 
though  inferior  in  this  quality  to  iron,  copper,  platinum,  or  silver. 
A  thread  of  gold  y|-|  -q  of  an  inch  in  diameter  will  sustain  a  weight 
of  150  pounds. 

The  fusing  point  of  gold  is  201 6°  F.  It  fuses  with  consider- 
able expansion,  and  on  cooling  contracts  more  than  any  other 
metal. 

On  account  of  the  want  of  affinity  of  gold  for  oxygen,  it  remains 
unaltered  in  the  longest  exposure ;  it  is  incapable  of  being  oxid- 
ized in  any  heat  that  may  be  applied  to  it,  and  is  only  volatilized 
with  great  difficulty  in  the  resistless  heat  of  the  oxyhydrogen 
blowpipe.  It  is  unaffected  by  the  most  concentrated  of  the  sim- 
ple acids,  but  is  readily  soluble  in  aqua  regia  or  nitro-muriatic  acid 
and  nitro-fluoric  acid. 

It  will  thus  be  seen  that  gold  possesses,  in  an  eminent  degree, 
those  general  properties  which  render  it  peculiarly  fit  for  the 
purposes  to  which  it  is  applied  in  the  practice  of  dental  prosthesis. 

Influence  of  Alloying  on  the  Properties  of  Gold. — The  term 
alloy  signifies  a  compound  of  any  two  or  more  metals,  as  brass, 
which  is  an  alloy  of  copper  and  zinc. 

Alloys,  in  respect  of  their  uses,  are  practically  new  metals,  and 
differ  in  many  important  respects,  both  in  their  chemical  and 
physical  characteristics,  from  the  constituent  metals  of  which 
they  are  composed.  A  more  particular  account  of  the  influence 
of  alloying  upon  the  general  properties  of  metals,  and  their  man- 
agement and  behavior  in  the  process  of  compounding,  will  be 
given  under  the  head  of  alloys  of  the  baser  metals.  As  gold  com- 
bines readily  with  most  metals,  some  of  the  more  prominent  con- 
ditions which  distinguish  its  alloys  will  be  given. 

The  malleability  of  gold  is,  strictly  speaking,  always  impaired 
by  its  union  with  other  metals.  This  effect  is  eminently  charac- 
teristic of  certain  contaminations,  as  those  with  arsenic,  tin,  anti- 
mony, bismuth,  lead,  etc. ;  while  with  certain  other  metals,  as  sil- 
ver, copper,  and  platinum,  unless  in  excess,  this  property  of  gold 
is  so  little  affected,  as  in  no  material  degree  to  interfere  with  its 
being  worked  into  any  desired  form  for  dental  purposes.  The 
ductility  of  gold  is  also  usually  diminished  by  its  incorporation 
with  foreign  metals ;  sometimes  in  a  remarkable  degree.     Gold  is 


METALS   EMPLOYED   IN   DENTAL   LABORATORY   OPERATIONS.  JI 

always  rendered  harder,  and  its  tenacity  is  generally  increased,  by 
alloying,  while  its  density  varies  with  the  particular  metal  or  met- 
als with  which  it  is  combined.  Thus  the  alloy  of  gold  with  either 
zinc,  tin,  bismuth,  antimony,  or  cobalt,  has  a  density  greater  than 
that  of  the  mean  of  its  constituents,  while  the  alloys  of  gold  hav- 
ing a  less  specific  gravity  than  the  mean  of  their  components  are 
those  with  silver,  iron,  lead,  copper,  iridium,  or  nickel.  Gold  is 
ordinarily  more  fusible  when  alloyed,  the  alloy  always  melting  at  a 
less  heat  than  that  required  to  fuse  the  most  refractory  constituent,  and 
oftentimes  less  than  the  more  fusible  component.  The  alloy  of  gold 
and  platinum  furnishes  an  example  of  the  former ;  the  platinum, 
which  in  its  uncombined  state  is  infusible  in  the  highest  heat  of  a 
blast-furnace,  forming  a  fusible  compound  with  gold,  the  melting- 
point  of  which  is  far  below  that  of  platinum.  Gold  solder,  com- 
posed of  gold,  copper,  and  silver,  affords  a  familiar  illustration  of 
the  latter,  the  alloy  melting  at  a  less  heat  than  that  required  to 
fuse  its  least  refractory  component,  silver.  Gold,  which  in  its  pure 
state  has  less  affinity  for  oxygen  than  any  other  metal,  is  rendered 
more  or  less  oxidizable  when  combined  with  other  metals. 

That  gold  alloys  tend  to  be  formed  in  definite  proportions  of 
their  constituents  would  appear  from  the  phenomenon  observed 
in  the  native  gold  of  the  auriferous  sands,  which  is  an  alloy  with 
silver  in  the  ratio  of  one  atom  of  silver,  united  to  four,  five,  six,  or 
twelve  atoms  of  gold,  but  never  with  a  fractional  part  of  an  atom. 
The  same  circumstance  is  noticed  in  connection  with  the  amalgam 
of  silver  and  mercury.  But  as  alloys  are  generally  soluble  in  each 
other,  the  definiteness  of  this  atomic  combination  is  obscured  and 
disappears  in  most  cases. 

Properties  of  Particular  Alloys  of  Gold. — The  metals  with 
which  gold  is  liable  to  be  contaminated  in  the  dental  laboratory 
are  zinc,  tin,  lead,  antimony,  bismuth,  iron  or  steel,  mercury,  and 
arsenic ;  as  also  excess  of  silver,  copper,  and  platinum.  As  several 
of  these  metals  when  alloyed  with  gold,  even  in  very  minute  quan- 
tities, are  highly  destructive  in  their  influence  upon  those  proper- 
ties which  adapt  this  metal  to  the  various  .wants  of  the  mechanical 
operator,  and  as  their  separation  is  often  attended  with  consider- 
able difficulty,  annoyance,  and  loss  of  time,  it  is  practically  im- 
portant that  care  should  be  taken  to  prevent,  as  far  as  practicable, 
the  admixture  of  any  one  or  more  of  them  with  the  gold  scrap,  fil- 


72  MECHANICAL   DENTISTRY. 

ings,  or  sweepings,  that  are  to  be  reconverted  into  proper  form 
for  use.  The  accidental  intrusion  of  these  metals,  however,  is,  to 
some  extent,  unavoidable,  and  as  an  acquaintance  with  the  more 
prominent  characteristics  or  sensible  properties  of  the  resulting 
alloys  sometimes  furnishes  valuable  indications  in  the  selection  of 
the  proper  reagents  employed  in  their  purification,  a  description 
of  individual  alloys  is  introduced. 

Tin,  antimony,  bismuth,  lead,  and  arsenic,  are  peculiarly 
prominent  in  their  effects  upon  the  malleability  of  gold;  either 
of  these  metals  in  exceedingly  minute  quantities  render  gold 
intractable. 

One  part  of  antimony  with  nine  parts  of  gold,  form  a  pale,  brittle 
alloy,  and  in  the  proportion  of  one  part  of  the  former  to  1920  of 
gold,  the  resulting  compound  is  too  brittle  to  admit  of  successful 
lamination. 

An  alloy  of  arsenic  with  gold  containing  ^q-  of  the  former  is  a 
gray,  brittle  metal,  while  in  the  proportion  of  -g-jjQ-,  the  malleabil- 
ity of  the  gold  is  seriously  impaired  without  suffering  any  change 
of  color.  So  energetic  is  the  influence  of  this  metal  on  gold  that 
the  latter  is  rendered  brittle  when  subjected  even  to  the  vapor  of 
arsenic. 

Tin,  lead,  and  bismuth  are  somewhat  analogous  to  arsenic  in 
their  influence  upon  the  malleability  of  gold,  either  of  them,  in  al- 
most inappreciable  quantities,  rendering  the  latter  metal  unman- 
ageable under  the  rollers.  One  part  of  lead  or  bismuth  to  1920 
of  gold  converts  the  latter  into  an  unmalleable  metal,  while  tin 
exceeds  either  in  its  remarkable  tendency  to  render  gold  hard  and 
brittle.  Alloys  of  gold  with  tin  are  of  a  light  color;  those  with 
lead  are  of  a  darker  complexion. 

Zinc  .with  gold  forms  a  brittle  alloy,  and  when  combined  in 
equal  proportions  is  exceedingly  hard,  white,  and  brittle.  Uniting 
or  incorporating  itself  less  intimately  with  the  gold  than  either 
lead  or  tin,  however,  it  not  infrequently  happens  that  portions  of 
the  ingot  will  be  brittle  while  others  remain,  in  some  degree, 
malleable;  so  that  the  bar,  when  rolled  out  in  the  form  of  plate, 
will  be  perforated  or  cracked  at  those  points  where  the  zinc  pre- 
dominates, while  remaining  portions  of  the  plate  retain  a  moder- 
ate degree  of  softness  and  pliability. 

The  working  properties  of  gold  are  not  sensibly  affected  by  the 


METALS   EMPLOYED   IN   DENTAL   LABORATORY  OPERATIONS.  73 

incorporation  of  very  small  quantities  of  iron,  as  an  alloy  of  these 
metals,  in  the  proportion  of  one  part  of  the  latter  to  eleven  of 
gold,  remains  malleable. 

Platinum,  in  itself  a  highly  refractory  metal,  is,  as  before  stated, 
rendered  fusible  in  combination  with  other  metals.  When  com- 
bined with  gold  in  small  proportions,  the  latter  is  rendered  harder 
and  more  elastic  without  having  its  malleability  practically  im- 
paired. Platinum  very  readily  affects  the  color  of  gold,  the  small- 
est quantities  rendering  the  alloy  pale  and  dull-colored. 

Silver  unites  with  gold  in  every  proportion,  and  is  the  chief 
metal  employed  in  the  reduction  of  gold  to  the  required  forms  for 
dental  uses.  It  renders  gold  more  fusible,  and  imparts  to  it 
increased  hardness  without  materially  affecting  its  malleability. 
The  alloy  is  light-colored  in  proportion  to  the  amount  of  silver 
introduced. 

Copper,  like  silver,  is  usually  combined  with  gold  in  the  forma- 
tion of  plate,  solders,  etc.,  and  hardens  and  renders  gold  tougher 
without  practically  impairing  its  malleability.  It  imparts  to  the 
alloy  a  deeper  red  color,  and  in  the  form  of  plate  is  capable  of 
receiving  a  polish  excelling  in  richness  and  brilliancy  any  other 
metal. 

The  foregoing  alloys  of  gold,  it  will  be  perceived,  are  such  as 
result  from  the  incorporation  with  gold  of  minute  proportions 
of  any  one  of  the  base  metals  mentioned,  and  possess  certain 
physical  characteristics  that  indicate,  with  tolerable  certainty,  the 
particular  alloying  component.  Thus,  for  example,  if  the  alloy  is 
light-colored  and  very  brittle,  the  presence  of  tin  may  be  sus- 
pected ;  if  brittle  and  dull-colored,  lead  is  indicated ;  if  grayish  or 
dull-colored,  but  still  malleable,  tough,  and  elastic,  platinum  is 
probably  present ;  if  unequally  malleable,  or  brittle  in  spots,  the 
presence  of  zinc  may  be  inferred. 

Alloys  of  gold,  however,  embracing  several  or  all  of  these  met- 
als in  varying  proportions,  are  sometimes  accidentally  formed,  in 
which  case  the  more  distinctive  features  which  characterize  the 
binary  compounds  are  lost  or  obscured. 


CHAPTER  IV. 

REFINING  GOLD. 

Elements  Employed. — The  separation  of  foreign  metals  from 
gold  by  what  is  termed  the  "dry  method,"  or  roasting,  is  effected 
by  the  action  on  them  of  either  oxygen,  chlorin,  or  sulphur,  con- 
verting them  into  oxids,  chlorids,  or  sulphurets.  Certain  com- 
pound substances  are  used  for  this  purpose  which,  when  heated 
and  decomposed,  yield  these  elements  in  sufficient  quantities  for 
the  purposes  specified.  The  refining  agents  in  common  use  are 
nitrate  of  potassa  (niter,  or  saltpeter),  which  yields  oxygen;  chlorid 
of  mercury  (corrosive  sublimate),  which  yields  chlorin;  and  sul- 
phuret  of  antimony  (crude  antimony),  which  yields  sulphur.  Other 
compounds  contain  these  elements,  but  those  mentioned  are 
generally  preferred  because  they  contain  them  abundantly,  are 
readily  decomposed  by  heat,  and  do  not  materially  interfere  with 
the  process  of  separation  by  the  introduction  of  troublesome  com- 
ponents into  the  alloy. 

Before  considering  specifically  the  different  modes  of  refining 
alloys  of  gold,  it  will  be  convenient  to  classify  the  different  forms 
of  gold  as  they  occur  in  working  this  metal  in  the  laboratory. 

i.  Plate-scrap  or  clippings,  and  plate-filings.  These,  if  proper 
care  is  taken  to  prevent  the  introduction  of  fragments  of  platinum, 
impure  filings,  or  particles  of  base  metals,  only  require,  provided 
they  were  originally  of  suitable  fineness,  to  be  remelted  and  again 
converted  into  plate  or  other  forms  for  use. 

2.  Mixed  filings,  and  fragments  containing  solder,  platinum, 
etc.  These,  when  melted  alone,  produce  an  alloy  more  or  less 
impoverished  in  proportion  to  the  quantity  and  quality  of  the 
foreign  metals  introduced  in  finishing  pieces  constructed  of  gold, 
and  should  either  be  separately  refined  by  roasting,  or  reduced  to 
pure  gold  by  the  "  humid  method,"  to  be  described  hereafter. 

3.  Sweepings.  This  form  embraces  many  impurities,  earthy 
and  metallic,  and  should  first  be  thoroughly  washed,  to  remove 

74 


REFINING    GOLD. 


75 


the  earthy  constituents,  after  which  the  remaining  metals  may 
either  be  mixed  with  class  second,  or  separately  refined.  Another 
and  perhaps  better  method,  is  to  fuse  together  the  sweepings  and 
substances  hereinafter  mentioned,  in  the  following  proportions : 
Of  sweepings,  eight  parts ;  chlorid  of  sodium,  four  parts ;  impure 
carbonate  of  potassa,  four  parts ;  impure  supertartrate  of  potassa, 
one  part;  and  nitrate  potassa,  half  part.  Mix  them  thoroughly 
together,  and  melt  in  a  crucible.  The  crucible  with  its  contents 
should  remain  in  the  fire  for  some  time,  in  order  to  secure  a  com- 
plete separation  of  the  metals  from  extraneous  matter. 

It  is  evident  from  the  above  classification  that  much  time  and 
labor  may  be  saved  by  preserving  these  forms  of  gold  separately 
as  they  accumulate  in  the  laboratory.  Separate  lap-skins  or  recep- 
tacles, therefore,  should  be  appropriated  to  the  working  of  gold, 
one  to  receive  scrap  and  unmixed  plate-filings,  which  may  be 
reconverted  into  plate  without  refining;  another  to  collect  the 
solder-filings,  and  such  impure  fragments  as  require  purification. 

Separation  of  Foreign  Metals  from  Gold. — The  most  trouble- 
some ingredients  which  find  their  way  into  gold  alloys  are  what 
are  commonly  called  base  metals,  as  tin,  lead,  zinc,  iron,  antimony, 
bismuth,  etc.  In  attempting  to  separate  these  metals  from  gold, 
it  is  not  a  matter  of  indifference  what  reagent  is  employed,  inas- 
much as  distinct  affinities  exist,  which  may  be  advantageously 
consulted.  If,  for  example,  zinc,  or  iron,  or  both  of  these  metals 
are  present  in  small  quantities,  any  compound  which  yields  oxy- 
gen will,  by  virtue  of  the  affinity  of  the  latter  for  these  metals, 
effect  their  separation  by  converting  them  into  oxids ;  hence, 
when  these  metals  are  to  be  got  rid  of,  nitrate  of  potassa  is  em- 
ployed. But  oxygen  has  a  feeble  affinity  for  tin,  and  when  this 
metal  is  present,  its  separation  is  better  effected  by  some  com- 
pound which  parts  with  chlorin  in  the  act  of  decomposition ; 
chlorid  of  mercury  is  therefore  used  for  the  purpose.  When  the 
alloy  of  gold  contains  a  number  of  these  metals  at  the  same  time, 
and  is  very  coarse,  sulphuret  of  antimony,  which  is  a  very  power- 
ful and  efficient  reagent,  should  be  resorted  to,  unless  the  opera- 
tor should  prefer,  and  which  is  the  better  way,  to  reduce  the  alloy 
to  pure  gold  by  the  "  humid  method." 

The  Dry  Method. — After  all  traces  of  iron  or  steel  have  been 
removed  from  the  gold  fragments  and  filings  by  passing  a  magnet 


j6  MECHANICAL   DENTISTRY. 

repeatedly  through  them,  the  latter  should  be  placed  in  a  clean 
crucible,  lined  on  the  inside  with  borax,  and  covered  either  with  a 
piece  of  fire-clay  slab,  or  broken  crucible.  Sheet-iron  has  been 
recommended  for  the  latter  purpose,  but  should  never  be  used,  as, 
when  highly  heated,  scales  form  on  the  surface,  and  are  liable  to  drop 
in  upon  the  fused  metals.  If  the  operation  is  likely  to  be  pro- 
tracted, an  inverted  crucible,  with  a  hole  in  the  bottom,  may  be 
securely  luted  to  the  top  of  the  one  containing  the  metals ;  the 
refining  agents  and  fluxes  being  introduced  through  the  opening 
in  the  upper  crucible.  These  are  then  placed  in  the  furnace,  on  a 
bed  of  charcoal,  or  what  is  better,  a  mixture  of  charcoal  and  coke, 
the  latter  being  built  up  around  the  crucible,  and  over  it  when 
covered  with  a  second  crucible,  care  being  taken  that  no  frag- 
ments of  fuel  are  permitted  to  fall  in  upon  the  fused  metals.  The 
process  is  as  follows : 

First  melt  the  alloy  at  a  high  temperature,  to  oxidize  the 
base  metals ;  the  refining  agents  may  then  be  added  in  small 
quantities  from  time  to  time,  and  the  heat  continued  from  half  an 
hour  to  an  hour,  according  to  the  coarseness  of  the  alloy.  The 
agents  first  employed  are  borax,  and  potassium  nitrate  (KN03).. 
The  latter  assists  the  oxidation  by  parting  with  its  oxygen,  when 
the  foreign  metals  will  generally  become  entirely  oxidized  and 
dissolved  in  the  slag. 

The  crucible  should  be  removed  from  the  fire,  and  the  metals 
allowed  to  cool  gradually.  The  crucible  may  now  be  broken  and 
the  button  of  gold  at  the  bottom  removed  and  separated  from  the 
slag  that  covers  it  with  a  hammer.  The  gold  should  then  be  put 
into  a  fresh  crucible  and  remelted  for  pouring  into  ingot-molds, 
which  should  be  previously  warmed  and  oiled  (see  page  89). 
This  treatment,  with  nitrate  of  potassa  and  borax,  will  usually  be 
sufficient,  as  most  metals  are  oxidizable.  If,  however,  after  ham- 
mering, annealing,  and  rolling  the  ingot,  it  should  still  be  found 
brittle,  it  must  be  remelted,  and  some  other  refining  agent  em- 
ployed to  remove  the  traces  of  the  base  metals.  If  it  is  known 
what  foreign  metal  is  present,  the  particular  reagent  which  will 
most  readily  attack  it  should  be  used.  But  if,  as  is  often  the  case, 
the  alloy  is  of  uncertain  composition,  or  contains  several  metals 
having  distinct  affinities,  the  process  becomes  to  some  extent 
experimental,  making  it  necessary  to  use  first  one  refining  agent 


REFINING   GOLD. 


77 


and  then  another,  until,  from  the  appearance  and  the  manipula- 
tion of  the  gold,  it  is  found  to  be  free  from  alloy.  The  special 
reagents  employed  are  as  follows : 

When  tin  or  lead  is  present,  add  mercuric  chlorid,  HgCl2  (cor- 
rosive sublimate),  and  zinc  chlorid,  ZnCl4,  or  lead  chlorid,  PbCl,, 
are  formed  and  with  the  mercury  volatilized  by  the  heat. 

When  silver  is  present,  add  to  the  molten  alloy  from  two  to 
four  times  its  weight  of  antimony  sulphid,  Sb2S3 ;  this  must  be 
added  carefully  and  a  little  at  a  time.  The  heat  decomposes  the 
sulphid.  The  sulphur  unites  with  the  silver  and  other  base  met- 
als, forming  sulphids,  while  the  antimony  unites  with  the  gold, 
forming  a  leaden-colored  alloy.  When  effervescence  has  ceased, 
remove  the  crucible  from  the  fire  and  allow  it  to  cool.  The  anti- 
mony and  gold  alloy  will  be  found  in  the  bottom  of  the  crucible, 
and  the  sulphids  on  the  surface. 

To  separate  the  antimony  from  the  gold,  remelt  the  alloy  and 
throw  upon  the  molten  mass  a  current  of  air  from  a  blowpipe. 
Antimony  oxid,  Sb203,  is  formed  and  volatilized ;  continue  the 
process  until  fumes  cease  to  be  given  off. 

When  iridium  is  present,  Prof.  Essig,  in  writing  upon  the  sub- 
ject, says  :  "  The  little,  hard  grains  occasionally  met  with  in  gold, 
upon  which  the  file  makes  no  impression,  consist  of  iridium,  or  a 
native  alloy  of  osmium  and  iridium,  and  are  not  combined  with 
the  gold,  but  merely  disseminated  through  it.  The  only  dry 
method  of  separating  it  from  gold  consists  in  alloying  the  latter 
with  three  times  its  weight  in  silver,  by  which  means  the  specific 
gravity  of  the  metal  is  so  much  lowered  that  iridium,  which  is 
very  infusible  and  of  a  specific  gravity  of  21.1,  will  subside  to  the 
bottom  of  the  crucible,  when  the  gold  and  silver  alloy  may  be 
poured  or  ladled  off.  As  some  of  the  gold  will  remain  with  the 
residue,  more  silver  must  be  melted  with  it,  the  operation  being 
repeated  several  times  until  nearly  all  the  gold  is  removed."  The 
gold  and  silver  alloy  may  then  be  separated  as  directed  above. 

When  Platinum  is  Present.  —  If,  after  treating  the  alloy  with 
the  reagents  enumerated,  it  should  be  found  malleable,  but  stiff  or 
elastic,  and  of  a  rather  dull  color,  it  is  due  to  the  presence  of 
platinum  ;  and  any  further  attempts  to  reduce  it  by  the  "  dry  proc- 
ess "  will  prove  unavailing.  It  must  then  be  subjected  to  what 
will  hereafter  be  described  as  the  "  humid  or  wet  method." 


yS  MECHANICAL   DENTISTRY. 

The  Humid  Method.- — When  it  is  desired  to  reduce  the  alloy 
to  pure  gold,  which  is  generally  advisable  whenever  the  gold  to  be 
refined  consists  of  very  coarse  filings,  fragments  of  plate  contain- 
ing large  quantities  of  solder,  linings  with  platinum  pins  attached, 
particles  of  base  metals,  etc.,  the  "  humid  or  wet  method,"  as  it  is 
called,  should  be  employed.  The  solvents  in  common  use  for  this 
purpose  are  nitric,  sulphuric,  and  nitro-muriatic  or  hydrochloric 
acid ;  but  as  the  desired  results  can  be  more  conveniently  and 
directly  obtained  by  the  use  of  the  latter,  or  hydrochloric  acid, 
this  most  available  method  alone  will  be  given.  The  following 
practical  remarks  on  the  subject  are  from  an  article  on  the  "  Man- 
agement of  Gold,"*  by  Professor  George  Watt: 

"  When  the  alloy  is  composed  of  metals  differing  but  little  in 
their  affinities  for  oxygen,  chlorin,  etc.,  we  resort  to  one  of  the  '  wet 
methods.'  And,  in  connection,  we  will  only  describe  the  one  which 
we  consider  the  most  convenient  and  effectual  for  the  practical 
dentist.    It  is  effectual  in  all  cases,  as  it  always  gives  us  pure  gold. 

"  Let  us,  then,  suppose  that  our  gold  alloy  has  become  contam- 
inated with  platinum  to  such  an  extent  that  the  color  and  elasticity 
of  the  plate  are  objectionable.  The  alloy  should  be  dissolved  in 
nitro-muriatic  or  hydrochloric  acid,  called  aqua  regia.  The  best 
proportions  for  aqua  regia  are  three  parts  of  hydrochloric  acid 
to  one  of  nitric.  If  the  acids  are  at  all  good,  four  ounces  of 
the  aqua  regia  will  be  an  abundance  for  an  ounce  of  the  alloy. 
The  advantage  of  using  the  acids  in  the  proportion  of  three  to 
one,  instead  of  two  to  one,  as  directed  in  most  of  the  text-books, 
is,  that  when  the  solution  is  completed  there  is  but  little,  if  any, 
excess  of  nitric  acid.  If  the  acids  be  '  chemically  pure,'  four  parts 
of  the  hydrochloric  to  one  of  the  nitric  produces  still  better  re- 
sults. 

"  By  this  process  the  metals  are  all  converted  into  chlorids ; 
and,  as  the  chlorid  of  silver  is  insoluble,  and  has  a  greater  speci- 
fic gravity  than  the  liquid,  it  is  found  as  a  grayish-white  powder 
at  the  bottom  of  the  vessel.  The  chlorids  of  the  other  metals, 
being  soluble,  remain  in  solution.  By  washing  and  pouring  off, 
allowing  the  chlorid  of  silver  time  to  settle  to  the  bottom,  the 
solution  may  be  entirely  separated  from  it. 

"  The  object  is  now  to  precipitate  the  gold  while  the  others  re- 

*  Dental  Register  of  the  West,  vol.  xii,  p.  251. 


REFINING   GOLD.  79 

main  in  solution.  This  precipitation  may  be  effected  by  any  one 
of  several  different  agents,  but  we  will  mention  only  the  protosul- 
phate  of  iron. 

"  This  salt  is  the  common  green  copperas  of  the  shops,  and,  as 
it  is  always  cheap  and  readily  obtained,  we  need  look  no  further. 
It  should  be  dissolved  in  clean  rain-water,  and  the  solution  should 
be  filtered,  and  allowed  to  settle  until  perfectly  clear.  Then  it  is 
to  be  added  gradually  to  the  gold  solution  as  long  as  a  precipitate 
is  formed,  and  even  longer,  as  an  excess  .will  the  better  insure  the 
precipitation  of  all  the  gold.  The  gold  thus  precipitated  is  a 
brown  powder,  having  none  of  the  appearances  of  gold  in  its 
ordinary  state.  The  solution  should  now  be  filtered,  or  the  gold 
should  be  allowed  to  settle  to  the  bottom,  where  it  may  be  washed 
after  pouring  off  the  solution.  It  is  better  to  filter  than  decant  in 
this  case,  as,  frequently,  particles  of  the  gold  float  on  the  surface, 
and  would  be  lost  in  the  washings  by  the  latter  process. 

"  Minute  traces  of  iron  may  adhere  to  the  gold  thus  precipi- 
tated. These  c^n  be  removed  by  digesting  the  gold  in  dilute  sul- 
phuric acid ;  and,  when  the  process  is  properly  conducted  thus 
far,  the  result  is  pure  gold,  which  may  be  melted,  under  carbonate 
of  potash,  in  a  crucible  lined  with  borax,  and  reduced  to  the  re- 
quired carat." 


CHAPTER  V. 

ALLOYS  OF  GOLD  FOR  DENTAL  PURPOSES. 

Gold  in  its  pure  state  is  rarely  employed  by  the  dentist  in  lab- 
oratory processes,  on  account  of  its  softness  and  flexibility ;  it  is, 
therefore,  usually  alloyed  with  such  metals  as  impart  to  it — with- 
out practically  impairing  either  its  malleability,  pliancy,  or  purity 
— the  degree  of  hardness,  strength,  and  elasticity  necessary  to  re- 
sist the  wear  and  strain  to  which  an  artificial  piece  constructed 
from  it  is  unavoidably  exposed  in  the  mouth. 

Reducing  Metals. — The  metals  with  which  gold  is  usually 
combined  are  copper  and  silver.  It  is  sometimes  reduced  with 
silver  alone,  many  regarding  the  introduction  of  copper  into  the 
alloy  as  objectionable,  as  plate  derived  from  it  is  supposed  to  be 
more  readily  tarnished  and  to  communicate  to  the  mouth  a  dis- 
agreeable metallic  taste.  This  is  unquestionably  true,  if,  as  is 
sometimes  the  case,  the  copper  used  is  in  excess ;  when,  in  addi- 
tion to  the  effects  mentioned,  gold,  so  debased,  may  become  a 
source  of  positive  injury  to  the  organs  of  the  mouth,  as  well  as  to 
the  general  health.  The  small  proportions  of  copper  usually  em- 
ployed in  forming  gold  plate,  however,  are  not  likely  to  produce, 
in  any  objectionable  degree,  the  consequences  complained  of,  un- 
less the  fluids  of  the  mouth  are  greatly  perverted.  If  gold  coin  is 
used  in  the  formation  of  plate,  it  may  be  sufficient  to  add  sil- 
ver alone,  inasmuch  as  copper  is  already  present;  though,  usually, 
additional  quantities  of  the  latter  metal  are  added. 

Required  Fineness  of  Gold  Plate. — Alloys  of  gold  to  be  per- 
manently worn  in  the  mouth  should  be  of  such  purity  as  will  most 
certainly,  under  all  the  contingencies  of  health  and  disease,  resist 
any  chemical  changes  that  would  tend  to  compromise  either  the 
comfort  or  health  of  the  patient.  Evils  of  no  inconsiderable  mag- 
nitude are  sometimes  inflicted,  either  through  ignorance,  careless- 
ness, or  cupidity,  by  a  disregard  of  this  important  requirement.  If 
the  general  health  of  the  patient  remained  always  uniformly  unim- 

80 


ALLOYS  OF  GOLD  FOR  DENTAL  PURPOSES.  8 1 

paired,  with  the  secretions  of  the  mouth  in  their  normal  state, 
gold  degraded  to  18  or  even  16  carats  fine,  would  undergo  no 
material  changes  in  the  mouth.  But  it  must  be  remembered 
that,  in  addition  to  the  corrosive  agents  introduced  into  the 
mouth  from  without,  a  variety  of  diseases,  local  and  constitutional, 
effect  important  changes  in  the  otherwise  bland  and  innoxious 
fluids  contained  therein,  which,  from  being  alkaline  or  neutral,  be- 
come more  or  less  acidulated.  Indigestion,  with  acid  eructations ; 
gastro-enteritis ;  ague ;  inflammatory  and  typhoid  fevers ;  brain 
affections ;  eruptive  diseases ;  rheumatism,  gout,  etc.,  are  some  of 
the  local  and  constitutional  disorders  almost  uniformly  imparting 
to  the  mucous  and  salivary  secretions  an  acid  reaction.  When 
this  condition  of  the  secretions  exists  in  connection  with  the  use 
of  gold,  readily  acted  on  chemically  by  reason  of  its  impoverish- 
ment, some  degree  of  irritation  of  the  tissues  of  the  oral  cavity  is 
likely  to  ensue.  Gold  plate  intended  to  be  introduced  into  the 
mouth  should  not,  therefore,  as  a  general  thing,  be  of  a  less  stand- 
ard of  fineness  than  from  18  to  20  carats.  It  may  exceed  this 
degree  of  purity  in  some  cases,  but  will  rarely  or  never,  unless 
alloyed  with  platinum,  admit  of  being  used  of  a  higher  carat 
than  the  present  American  coin,  which  is  21.6  carats  fine. 

Formulas  for  Gold  Plate  used  as  a  Base  for  Artificial  Den- 
tures.— Any  of  the  following  formulas  may  be  employed  in  the 
formation  of  gold  plate  to  be  used  as  a  base  or  support  for  artifi- 
cial dentures.  The  relative  proportions  of  the  alloying  com- 
ponents may  be  varied  to  suit  the  peculiar  views  or  necessities  of 
the  manipulator.  The  estimated  carat  of  the  appended  formulas 
is  based  on  the  fineness  of  the  American  gold  pieces  coined  in 
1837  and  thereafter. 

GOLD  PLATE  EIGHTEEN  CARATS  FINE. 
Formula  No.  1.  Formula  No.  2. 

18  dwts.  pure  gold,  20  dwts.  gold  coin, 

4  dwts.  fine  copper,  2  dwts.  fine  copper, 

2  dwts.  fine  silver.  2  dwts.  fine  silver. 

GOLD   PLATE   NINETEEN    CARATS   FINE. 
Formula  No.  3.  Formula  No.  4. 

19  dwts.  pure  gold,  20  dwts.  gold  coin, 

3  dwts.  copper,  25  grs.  copper, 

2  dwts.  silver.  40  +  grs-  silver. 

6 


82  MECHANICAL  DENTISTRY. 

GOLD   PLATE  TWENTY  CARATS   FINE. 
Formula  No.  5.  Formula  No.  6. 

20  dwts.  pure  gold,  20  dwts.  gold  coin, 

2  dwts.  copper,  18  grs.  copper, 

2  dwts.  silver.  20  +   grs.  silver. 

GOLD   PLATE  TWENTY-ONE  CARATS  FINE. 

Formula  No.  7.  Formula  No.  8.  Formula  No.  0. 

21   dwts.  pure  gold,  20  dwts.  gold  coin,  20  dwts.  gold  coin, 

2  dwts.  copper,  13  +    grs.  silver.  6  grs.  copper, 

1   dwt.  silver.  ?s   grs>  platinum. 

GOLD   PLATE  TWENTY-TWO   CARATS   FINE. 

Formula  No.  10. 
22  dwts.  pure  gold, 

1   dwt.  fine  copper, 
18  grs.  silver, 

6  grs.  platinum. 

The  union  of  platinum  with  gold,  as  in  Formula  No.  10,  fur- 
nishes an  alloy  rich  in  gold,  while  it  imparts  to  the  plate  derived 
from  it  a  reasonable  degree  of  stiffness  and  elasticity;  preserves 
in  a  good  degree  the  characteristic  color  of  fine  gold ;  and  does 
not  materially  impair  its  susceptibility  of  receiving  a  high  polish. 
The  amount  of  gold  coin  given  in  Formula  No.  9  may  be  reduced 
with  platinum  alone,  adding  to  it  from  eight  to  twelve  grains ;  in 
which  case,  although  the  carat  of  the  alloy  is  lowered,  its  absolute 
purity  remains  unaffected,  and  plate  formed  from  it  will  better 
resist  any  changes  in  the  mouth  than  gold  coin  itself. 

Formulas  for  Gold  Plate  used  for  Clasps,  Wire,  Stays  or 
Backings,  Dowels,  etc. — Gold  used  in  the  formation  of  clasps, 
backings,  etc.,  is  improved  for  these  purposes  by  the  addition  of 
sufficient  platinum  to  render  it  firmer  and  more  elastic  than  the 
alloys  ordinarily  employed  in  the  formation  of  plate  as  a  base. 
The  advantages  of  this  elastic  property,  in  its  application  to  the 
purposes  under  consideration,  are,  that  clasps  formed  from  such 
alloys  will  adapt  themselves  more  accurately  to  the  teeth,  as,  when 
partially  spread  apart  on  being  forced  over  the  crowns,  they  will 
spring  together  again  and  accurately  embrace  the  more  contracted 
portions.  In  the  form  of  stays  or  backings,  additional  strength 
being  imparted,  a  less  amount  of  substance  will  be  required ;  the 
elasticity  of  these  supports,  also,  will  not  only  lessen  the  chances 


ALLOYS  OF  GOLD  FOR  DENTAL  PURPOSES.  83 

of  accident  to  the  teeth  themselves  in  mastication  and  otherwise, 
but  preserve  their  proper  position  when  temporarily  disturbed  by 
any  of  the  forces  applied  to  them.  The  same  advantages  last  men- 
tioned are  obtained  from  this  property  in  the  use  of  metallic 
pivots. 

Formula  No.  1.  Formula  No.  2. 

20  dwts.  pure  gold,  20  dwts.  coin  gold, 

2  dwts.  fine  copper,  8  grs.  fine  copper, 

1   dwt.  fine  silver,  10  grs.  silver, 

1   dwt.  platinum.  20  grs.  platinum. 

The  alloy  derived  from  either  of  these  formulas  will  be  20 
carats  fine. 

Gold  Solders.  —  Solders  are  a  class  of  alloys  by  means  of  which 
the  several  pieces  of  the  same  or  of  different  metals  are  united  to 
each  other.  They  should  be  more  fusible  than  the  metals  to  be 
united,  and  should  consist  of  such  components  as  possess  a  strong 
affinity  for  the  substances  to  be  joined.  They  should  also  be  as 
fine  as  the  metals  to  which  they  are  applied  will  admit  of  without 
endangering  the  latter.  Solders  of  different  degrees  of  fineness, 
therefore,  should  always  be  provided  to  make  selections  from. 

The  use  of  solders  of  doubtful  or  unknown  composition  should 
be  avoided,  and  hence  they  should  be  compounded  either  from 
pure  gold  or  gold  coin. 

The  following  formula  taken  from  Prof.  Harris's  work  on 
"  Dental  Surgery,"  page  666,  recipe  No.  3,  may  be  used  in  connec- 
tion with  18  or  20  carat  gold  plate,  and  is  16  carats  fine : 

6   dwts.  pure  gold, 

2  dwts.  rosette  copper, 

1    dwt.  fine  silver. 

Recipes  Nos.  1  and  2,  page  663  of  same  work,  are  too  coarse  to 
be  introduced  into  the  mouth ;  the  former  being  a  fraction  below 
14  carats,  while  the  latter  is  still  more  objectionable,  exceeding 
but  little  i2J/2  carats. 

Formula  No.  I  of  the  following  recipes  is  a  fraction  over  15 
carats  fine :  and  No.  2  furnishes  a  solder  18  carats  fine : 

Formula  No.  i.  Formula  No.  2. 

6  dwts.  gold  coin,  Gold  coin,  30  parts, 

30  grs.  silver,  Silver,  4       " 

20  grs.  copper,  Copper,  1  part, 

10  grs.  brass.  Brass,  1     " 


84  MECHANICAL   DENTISTRY. 

In  the  reduction  of  gold  for  solders,  Dr.  Dorrence  recommends 
the  use  of  what  he  calls  "  solder  alloy."  This  is  derived  from  the 
following  formula : 

1  part  pure  silver, 

2  parts  pure  zinc, 

3  parts  pure  copper. 

The  copper  and  silver  are  melted  without  flux,  in  a  clean  cru- 
cible which  is  well  lined  with  borax;  the  zinc  is  then  added  in 
small  quantities  as  rapidly  as  may  be  without  chilling  the  molten 
mass  so  that  it  loses  its  fluidity,  meanwhile  stirring  it  with  a  clay 
pipe-stem  or  rod,  or  a  white-wood  stick,  until  the  profuse  fumes 
of  the  burning  zinc  just  pass  off,  when  pour  immediately  into  an 
ingot-mold,  or  into  clean  water  in  a  clean  wooden  pail.  The  met- 
als entering  into  the  composition  of  this  solder  alloy  should  be 
absolutely  pure,  especially  should  they  be  free  of  arsenic,  anti- 
mony, cadmium,  etc.,  in  which  case  not  only  the  alloy,  but  gold 
and  silver  solders  made  from  it,  will  be  tough  and  easy-flowing. 
Inasmuch  as  the  zinc,  in  compounding  the  alloy,  has  not  been  pro- 
tected from  oxidation,  if  it  has  been  cast  at  the  proper  moment,  it 
will  be  found  present  in  about  its  combining  weight.  Both  gold 
and  silver  solders  made  with  this  alloy  will,  as  has  been  stated,  be 
found  very  tough,  and  easy-flowing,  the  range  of  proportion  most 
desirable  being,  for  gold  solder  from  20  to  12  carats,  or  from  15  to 
50  per  cent,  of  alloy.  Dr.  D.  very  properly  says,  however,  that  the 
12  carat  or  50  per  cent,  solder  is  too  coarse  for  dental  work.  From 
to  to  15  per  cent,  of  the  alloy  added  to  gold  coin  is  recommended 
as  a  suitable  solder  in  the  construction  of  coin-gold  crowns. 

Zinc,  as  a  constituent  of  solders,  is  used  principally  with  a  view 
of  rendering  them  more  fusible  without  materially  debasing  them 
if  the  proper  proportion  is  observed.  Its  employment  under  any 
circumstances  has  been  objected  to  by  some,  on  the  ground  that 
the  alloy  is  more  readily  tarnished  in  the  mouth,  is  more  brittle, 
and  that  it  furnishes  more  favorable  conditions  for  galvanic  action. 
These  objections  only  hold  good  when  zinc  is  used  in  excess. 
When  employed  in  quantities  sufficient  only  to  make  the  gold  flow 
readily  and  evenly  at  a  diminished  heat,  it  is  claimed  that  the  base 
metal  used  in  these  alloys  is  chiefly  consumed  in  the  process  of 
soldering,  leaving  a  residuum  of  gold  alloy  equal,  or  nearly  so,  in 
purity  to  solder  not  so  contaminated.    If  such  is  the  case  they  are 


ALLOYS  OF  GOLD  FOR  DENTAL  PURPOSES.  8^ 

acceptable  alloys  for  soldering  purposes,  inasmuch  as  it  is  not 
only  desirable  to  have  an  easy-flowing  solder,  but  one  which  shall 
have  as  little  affinity  as  possible  for  acids  often  found  associated 
with  the  fluids  of  the  mouth.  Care  should  be  taken  to  add  no 
more  zinc  than  is  necessary  to  make  the  solder  flow  freely  under 
a  heat  that  may  be  safely  applied,  without  danger  of  melting  the 
pieces  to  be  united. 

Method  of  Reducing  Gold  to  a  Lower  or  Raising  it  to  a  Higher 
Standard  of  Fineness,  and  of  Determining  the  Carat  of  any  Given 
Alloy. — In  the  process  of  compounding  gold  for  dental  purposes, 
the  manipulator  should  always  aim  at  exactness  in  the  quantity 
and  relative  proportions  of  the  reducing  components,  and  should 
be  able  to  determine  precisely  the  purity  of  the  metals  he  em- 
ploys. Gold  alloys  are  too  often  arbitrarily  compounded,  and 
used  without  any  adequate  knowledge  of  their  qualities  or  prop- 
erties ;  and  formulas,  taken  on  trust,  are  employed  without  any 
certain  knowledge  of  the  quality  of  the  alloys  they  produce. 

That  we  may  know  certainly  the  quality  of  the  gold  alloys  used 
in  the  laboratory  without  resorting  to  the  inconvenient  process  of 
analysis  or  assaying,  they  should  always  be  made  either  from  pure 
gold  or  gold  coin,  the  standard  of  these  being  definitely  fixed. 
But  as  the  process  of  procuring  pure  gold  is  somewhat  tedious  and 
troublesome,  gold  coin  is  very  generally  employed  for  the  purpose. 
The  amount  of  alloy  necessary  to  reduce  either  pure  or  coin  gold 
to  any  particular  standard,  and  the  method  of  ascertaining  the 
carat  or  fineness  of  any  given  alloy,  may  be  readily  determined 
by  a  few  simple  rules.  The  following  practical  remarks  on  the 
method  are  taken  from  an  article  on  "  Alloying  of  Gold,"*  by 
Professor  Watt : 

"  i.  To  Ascertain  the  Carat  of  any  Given  Alloy. — The  propor- 
tion may  be  expressed  as  follows : 

"As  the  weight  of  the  alloyed  mass  is  to  the  weight  of  gold 
it  contains,  so  is  24  to  the  standard  sought.  Take,  for  example, 
Harris's  No.  3  gold  solder: 

Pure  gold,    6  parts. 

"     silver,    2 

"     copper,    1   part. 

Total,    9  parts. 

*  Dental  Register  of  the  West,  vol.  x,  p.  396. 


86  MECHANICAL   DENTISTRY. 

"  The  total  proportion  would  be  expressed  thus : 

9  :  6  :  :  24  :   16. 

"  From  this  any  one  can  deduce  the  following : 

"  Rule. — Multiply  24  by  the  weight  of  gold  in  the  alloyed  mass, 
and  divide  the  product  by  the  weight  of  the  mass ;  the  quotient  is 
the  carat  sought. 

"  In  the  above  example,  24  multiplied  by  6,  the  quantity  of 
gold,  gives  144,  which,  divided  by  9,  the  weight  of  the  whole 
mass,  gives  16.  Hence,  an  alloy  prepared  as  above  is  16  carats 
fine. 

"  As  another  example,  under  the  same  rule,  take  Harris's  No. 
1  solder: 

22    carat   gold,    48  parts. 

Silver 16 

Copper,    12 

Total,    76  parts. 

"  Now,  as  the  gold  used  is  but  22  carats  fine,  one-twelfth  of  it 

is  alloy.     The  -fa  of  48  is  4,  which  subtracted  from  48  leaves  44. 

The  statement  then  is  : 

76  :  44  ::  24  :   13.9. 

"  This  solder,  therefore,  falls  a  fraction  below  14  carats. 

"  2.  To  Reduce  Gold  to  a  Required  Carat. — The  proportion 
may  be  expressed  as  follows : 

"  As  the  required  carat  is  to  24,  so  is  the  weight  of  the  gold  used 
to  the  weight  of  the  alloyed  mass  when  reduced.  The  weight  of 
gold  subtracted  from  this  gives  the  quantity  of  alloy  to  be  added. 

"  For  example,  reduce  six  ounces  of  pure  gold  to  16  carats. 

"  The  statement  is  expressed  thus : 

16  :  24  :  :  6  :  9. 

"  Six  subtracted  from  nine  leaves  three,  which  is  the  quantity 
of  alloy  to  be  added.     From  this  is  deduced  the  following : 

"  Rule. — Multiply  24  by  the  weight  of  pure  gold  used,  and 
divide  the  product  by  the  required  carat.  The  quotient  is  the 
weight  of  the  mass  when  reduced,  from  which  subtract  the  weight 
of  the  gold  used,  and  the  remainder  is  the  weight  of  alloy  to  be 
added. 


ALLOYS  OF  GOLD  FOR  DENTAL  PURPOSES.  87 

"  As  another  example  under  the  same  rule,  reduce  one  penny- 
weight of  22  carat  gold  to  18  carats. 

"  As  the  gold  is  only  22  carats  fine,  one-twelfth  of  it  is  already 
alloy.  The  one  pennyweight,  therefore,  contains  but  22  grains  of 
pure  gold.     The  statement  is,  therefore,  thus  expressed : 

18  :  24  :  :  2.2  :  29J/3. 

"  Twenty-two  subtracted  from  29%  leaves  7%.  Therefore, 
each  pennyweight  of  22  carat  gold  requires  7%  grains  of  alloy  to 
reduce  it  to  18  carats. 

"  3.  To  Raise  Gold  to  a  Higher  Carat. — This  may  be  done  by 
adding  pure  gold  or  a  gold  alloy  finer  than  that  required.  The 
principle  of  the  rule  may  be  set  forth  in  the  following  general  ex- 
pression : 

"  As  the  alloy  in  the  required  carat  is  to  the  alloy  in  the  given 
carat,  so  is  the  weight  of  the  alloyed  gold  used  to  the  weight  of 
the  reduced  alloy  required.  The  principle  may  be. practically  ap- 
plied by  the  following: 

"  Rule. — Multiply  the  weight  of  the  alloyed  gold  used  by  the 
number  representing  the  proportion  of  alloy  in  the  given  carat, 
and  divide  the  product  by  that  representing  the  proportion  of  al- 
loy in  the  required  carat;  the  quotient  is  the  weight  of  the  mass 
when  reduced  to  the  required  carat  by  adding  fine  gold : 

"  To  illustrate  this,  take  the  following  example : 

"  Raise  one  pennyweight  of  16  carat  gold  to  18  carats. 

"  The  numbers  representing  the  proportions  of  alloy  in  this  ex- 
ample are  found  by  respectively  subtracting  18  and  16  from  24. 
The  statement  is,  therefore  : 

6  :  8  :  :   1  :  xyi, 

from  which  it  follows  that  to  raise  one  pennyweight  of  16  carat 
gold  to  18  carats,  there  must  be  Y$  of  a  pennyweight  of  pure  gold 
added  to  it. 

"  But  suppose  that,  instead  of  pure  gold,  we  wish  to  effect  the 
change  by  adding  22  carat  gold.  The  numbers,  then,  respectively 
representing  the  proportions  of  the  alloy  would  be  found  by  sub- 
tracting, in  the  above  example,  16  and  18  from  22,  and  the  state- 
ment would  be : 

4  :   6  :   :    1   :    iV2. 


88  MECHANICAL   DENTISTRY. 

"  It  follows,  then,  that  to  each  pennyweight  of  16  carat  gold  y2 
of  a  pennyweight  of  22  carat  gold  must  be  added  to  bring  it  to  18 
carats. 

"  By  the  above  rules,  we  think  the  student  will  be  able,  in  all 
cases,  to  calculate  the  fineness  or  quality  of  his  gold,  and  to  effect 
any  reduction,  whether  ascending  or  descending,  which  he  may 
desire." 


CHAPTER  VI. 

METHOD  OF  CONVERTING  GOLD  ALLOYS   INTO   THE  REQUIRED 
FORMS  FOR  DENTAL  PURPOSES. 

Manner  of  Procuring  an  Ingot. — The  gold  to  be  molded  in  the 
form  of  ingot  is  put  into  a  clean  crucible  lined  on  the  inside  with 
borax,  and  placed  in  the  furnace.  When  the  contained  metals  are 
perfectly  fused,  the  crucible  should  be  removed  from  the  fire  with 
a  pair  of  tongs,  and  the  contents  poured  quickly  but  carefully  into 
the  ingot-molds ;  the  latter  being  placed  conveniently  near  the 
mouth  of  the  furnace,  as  the  molten  metals  soon  become  chilled 
on  exposure  to  the  open  air.     Before  pouring,  the  molds,  if  made 

Fig.  40. 


of  iron,  should  be  moderately  heated  and  oiled,  or  coated  with 
lamp  smoke  by  holding  their  inner  surfaces  over  the  flame  of  an 
oil  lamp  or  gas-jet. 

Ingot-molds  are  constructed  of  various  substances,  but  those  in 
most  common  use  are  formed  of  iron,  and,  for  gold,  are  generally 
about  two  inches  square  and  from  y%  to  y^  of  an  inch  thick  (Fig. 
40).  They  should  be  slightly  concave  on  their  inner  surfaces,  to 
compensate  for  the  greater  shrinkage  of  the  gold  in  the  center 
than  at  the  margins  of  the  ingot. 

Soapstone  is  sometimes  employed  for  the  same  purpose,  and  is 

89 


9<D  MECHANICAL   DENTISTRY. 

preferred  by  some.  Molds  made  from  this  substance  should  also 
be  warmed  and  oiled  before  pouring  the  metals. 

Molds  are  also  made  from  charcoal,  which  is  highly  recom- 
mended for  the  purpose,  though  it  requires  to  be  frequently  re- 
newed. Prof.  Gorgas,  in  commenting  on  the  relative  fitness  or 
value  of  the  several  substances  mentioned,  says  :  "  Iron  is  perhaps 
the  most  convenient ;  soapstone  gives,  with  the  same  gold,  a 
tougher  ingot;  whilst  with  charcoal,  the  greatest  toughness  of 
metal  is  obtained,  so  far  as  the  nature  of  the  ingot-mold  can 
modify  it.  Pig-iron,  from  the  same  furnace,  run  into  iron  molds, 
may  be  white  and  brittle ;  or  into  sand  molds,  gray  and  less  brit- 
tle; or  into  charcoal,  dark  gray  and  soft.  Some  such  molecular 
arrangement  of  gold,  due  to  its  manner  of  cooling,  is  probably  the 
correct  explanation  of  the  fact  that  a  charcoal  mold  yields,  other 
things  being  equal,  a  tougher  ingot  than  iron." 

Charcoal  ingot-molds  may  be  very  easily  and  quickly  made  as 
follows :  Selecting  a  close-grained  compact  piece,  of  suitable  size, 
cut  through  it  with  a  saw,  and  then  rub  the  divided  surfaces  to- 
gether until  perfect  coaptation  is  secured.  The  required  size- and 
shape  of  the  mold  is  then  cut  out  in  one  section  of  the  block ;  or 
a  strip  of  sheet-iron,  a  little  broader  than  the  required  thickness 
of  the  ingot,  being  bent  into  proper  form,  is  placed  between  the 
two  pieces,  with  the  edges  partially  imbedded,  and  the  whole 
secured  in  place  by  binding  with  wire,  or  with  the  use  of  clamps. 

Asbestos  Molds. — Comparatively  inexpensive,  and  at  the  same 
time  more  convenient  and  durable  contrivances  designed  for  the 
same  purpose,  combining  both  crucible  and  mold,  and  embracing 
the  special  advantages  claimed  for  charcoal,  may  be  obtained  at 
the  dental  depots.  One  of  the  simplest  forms  of  this  kind  is  the 
asbestos  melting  and  ingot  block  shown  in  Fig.  41.  When  in  use, 
place  a  piece  of  charcoal  over  the  bowl-shaped  portion  of  the  in- 
got block,  as  it  facilitates  heating  the  metal.  The  small  asbestos 
slab  being  placed  in  position  to  complete  the  mold,  and  retained 
in  place  by  clamping,  the  metal,  when  sufficiently  fused,  is  poured 
into  the  mold  by  tipping  the  block.  The  bowl  or  crucible  has  a 
thin  coating  of  whiting,  to  prevent  borax  or  other  flux  from  ad- 
hering. Should  this  occur,  however,  rub  a  little  moist  whiting  in 
the  bowl.  The  sides  of  the  block  are  encased  in  strips  of  wood, 
to  protect  the  hands  from  heat. 


FORMING   GOLD   ALLOYS    FOR   DENTAL    USE. 


91 


Carbon  Molds. — A  very  ingenious,  convenient,  and  useful  ap- 
paratus, combining  crucible  and  ingot-mold,  by  the  use  of  which 
ingots  of  gold,  silver,  etc.,  may  be  quickly  obtained  without  the 
use  of  a  furnace,  is  shown  in  Fig.  42.  The  crucible  is  of  molded 
carbon,  and  is  supported  in  position  by  an  iron  side-plate.     A 

Fig.  41. 


clamp  holds  crucible  and  ingot-mold  in  position,  swiveling  on  a 
cast-iron  stand. 

The  metal  to  be  melted  is  placed  in  the  crucible,  and  the  flame 
of  the  blowpipe  directed  on  it  until  it  is  perfectly  fused.  The 
waste  heat  serves  to  make  the  ingot-mold  hot,  and  the  whole  is 

Fig.  42. 


tilted  over  by  means  of  the  upright  handle  at  the  back  of  the 
mold.  With  this  simple  instrument  a  sound  ingot  may  be  ob- 
tained at  any  time  in  about  two  minutes. 

Aside  from  the  greater  convenience  and  cleanliness,  as  com- 
pared with  the  older  method  in  which  draft-furnace  heat  is  used, 


92  MECHANICAL   DENTISTRY. 

there  is  great  economy  of  time  in  the  use  of  the  last-named  appli- 
ance combining  crucible  and  mold,  since  an  ingot  may  be  thus 
obtained,  with  the  use  of  the  bellows  blowpipe,  in  from  two  to 
three  minutes.  It  is  suitable  for  melting  from  two  to  four  ounces 
of  gold  or  silver. 

It  not  infrequently  happens  that,  at  the  first  pouring,  the  metals 
arrange  themselves  in  the  ingot  in  accordance  with  the  density  of 
the  several  components,  those  of  greater  specific  gravity  passing  to 
the  bottom,  and  the  lighter  metals  remaining  above.  Whenever 
this  occurs,  the  ingot  must  be  broken  into  pieces  and  remelted ; 
this  should  be  repeated,  if  necessary,  until  the  alloy  assumes  a  per- 
fectly homogeneous  appearance.  It  should  then  be  annealed  in 
hot  ashes,  which  softens  the  gold  and  removes  the  adhering  grease. 

Forging. — Before  laminating,  the  ingot  should  be  reduced 
somewhat  in  thickness  ( by  placing  it  on  an  even-faced  anvil  or 
other  equally  smooth  and  resistant  surface,  and  subjecting  it  to 
repeated  blows  with  a  tolerably  heavy  hammer.  It  should  be  fre- 
quently annealed,  and  the  process  of  forging  continued,  alter- 
nately hammering  and  annealing,  until  the  ingot  is  reduced  one- 
half  or  more  in  thickness. 

Laminating  or  Rolling. — The  reduced  ingot,  well  annealed,  is 
next  laminated  or  spread  out  into  a  sheet  of  greater  or  less  thin- 
ness by  passing  it  repeatedly  between  two  strong,  highly-polished 
cylindrical  steel  rollers.  The  mills  used  for  the  purpose  are 
variously  constructed,  the  plainest  forms  being  very  simple  in 
their  mechanism,  while  others,  or  geared  mills,  are  more  compli- 
cated, and  are  constructed  with  a  view  to  a  greater  augmentation 
of  power,  precision,  and  certainty  of  action.  Fig.  43  illustrates 
such  a  mill. 

In  laminating,  the  rollers  should  first  be  adjusted  equidistant 
at  both  ends,  and  this  uniformity,  as  they  are  approximated  from 
time  to  time,  should  be  preserved  throughout.  At  every  passage 
of  the  gold  bar  between  the  rollers,  the  distance  between  the  lat- 
ter should  be  diminished,  care  being  taken  that  the  approxima- 
tion be  insufficient  to  clog  or  impede  the  free  action  of  the  mills. 
The  gold,  which,  in  time,  becomes  hard  and  brittle,  and  liable  to 
crack  in  the  mills,  should  be  frequently  and  well  annealed  by 
bringing  it  to  a  full  red  heat ;  this  restores  the  pliancy  of  the  gold 
and  facilitates  the  operation  in  the  press. 


FORMING    GOLD    ALLOYS    FOR    DENTAL    USE. 


93 


When  the  ingot  has  been  extended  in  one  direction  as  far  as 
may  be  desired,  it  should  always  be  reannealed  before  turning  it 
in  the  mills ;  a  neglect  of  this  precaution  will  seriously  interfere 
with  the  working  of  the  gold  by  twisting  or  doubling  the  plate 
upon  itself ;  and  in  some  instances,  provided  the  gold  has  not 
been  well  annealed  throughout  the  operation,  or  is  in  any  consid- 


Fig.  43. 


erable  degree  unmalleable,  the  plate  will  be  torn  across  and  ren- 
dered unfit  for  use. 

A  thin  or  retreating  edge  may  be  given  to  the  plate  at  any  de- 
sired point  or  points  by  passing  such  portions  part  way  between 
the  rollers  and  withdrawing;  repeating  this,  with  the  rollers 
brought  a  little  nearer  to  each  other  every  time  the  plate  is 
introduced  between  them,  and  decreasing  the  distance  the  plate 


94 


MECHANICAL   DENTISTRY. 


passes  each  time,  until  it  is  reduced  to  as  thin  an  edge  as  may  be 
desired. 

Standard  Gage  Plate. — The  degree  of  attenuation  obtained  by- 
rolling  is  determined  by  what  is  called  a  gage  plate  (Fig.  44). 
This  instrument  is  usually  circular  or  oblong  in  form,  and  is 
marked  at  intervals  on  its  edge  by  cross-cut  grooves,  or  fissures, 
which  successively  diminish  in  size  and  are  indexed  by  numbers 
ranging  from  5  to  36.  The  sizes  of  the  grooves  diminish  with 
the  ascending  numbers.  During  the  operation  of  rolling,  the 
plate  should  be  tested,  from  time  to  time,  by  the  gage,  to  deter- 
mine when  it  has  undergone  sufficient  attenuation. 

Fig.  44. 


Thickness  of  Gold  Plate  Required  as  a  Base  for  Artificial 
Dentures.  —  In  prescribing  the  thickness  of  plate  proper  for  the 
purpose  indicated,  no  estimate  can  be  given  that  will  apply  to  all 
cases,  as  certain  conditions  of  the  mouth,  to  be  mentioned  here- 
after, will  suggest  some  modifications  in  this  respect.  Usually, 
however,  plate  for  entire  upper  dentures  should  correspond  in  thick- 
ness with  number  26  of  the  gage  plate;  for  the  lower  jaw,  number 
24  may  be  used;  while  for  partial  upper  pieces,  an  intermediate 
number  may  be  chosen,  unless  atmospheric  pressure-plates  are 
used,  when  the  number  recommended  for  full  upper  sets  may  be 
employed. 

Thickness  of  Plate  for  Clasps,  Backings,  etc. — Plate  for  these 


FORMING    GOLD   ALLOYS    FOR   DENTAL    USE. 


95 


purposes  should  usually  correspond  with  number  22  of  the  gage ; 
a  less  amount  of  substance,  as  before  stated,  being  required  when 
the  alloy  has  incorporated  with  it  a  small  proportion  of  platinum. 

Reduction  of  Gold  Solders  into  Proper  Form  for  Use. — The 
method  of  converting  gold  solders  into  the  form  of  plate  does 
not  differ  from  that  already  described  in  the  manufacture  of  plate 
as  a  base,  except  that  when  zinc  or  brass  is  used,  the  latter  should 
be  added  after  the  other  constituents  are  completely  fused,  and 
then  instantly  poured,  to  prevent  undue  wasting  of  the  base  met- 
als by  a  too  protracted  heat. 

The  solder  should  be  reduced  to  plate  somewhat  thinner  than 
that  used  for  upper  dentures,  28  of  the  gage  plate.     It  is  customary 


Fig.  45. 


© (?  S  vi  ri  S  1'  8  ?• 

•  0  &  •  ©  S  •  ©  :£)  • 


sometimes  to  roll  the  solder  into  very  thin  ribbons,  but  this  is 
objectionable  for  the  reason  that  a  greater  amount  of  the  alloy- 
ing metals,  being  exposed  in  a  given  surface  to  the  action  of  the 
heat  in  soldering,  are  burnt  out  or  oxidated,  which  interrupts  the 
flow  and  weakens  the  attachment  between  the  solder  and  plate. 

Method  of  Obtaining  Gold  Wire. — To  convert  gold  or  its  al- 
loys into  the  form  of  wire,  the  operator  should  be  provided  with  a 
draw-plate,  a  vise,  and  a  pair  of  flat-nosed  pliers.  A  draw-plate 
(Fig.  45)  is  an  oblong  piece  of  steel,  pierced  with  a  regular  grada- 
tion of  holes,  or  a  series  of  progressively  diminishing  apertures, 
through  which  the  gold  bar,  reduced  to  a  rod,  is  forced  and  made 
to  assume  the  form  and  dimensions  of  the  hole  through  which  it 


96 


MECHANICAL   DENTISTRY. 


is  last  drawn.  The  holes  are  formed  with  a  steel  punch,  and  are 
enlarged  on  the  side  where  the  wire  enters  and  diminish  with  a 
gradual  taper  to  the  other  side.  A  draw-bench  is  sometimes  em- 
ployed in  extending  the  wire,  the  power  being  applied  by  a 
toothed-wheel,  pinion,  and  rack-work,  and  is  moved  by  the  hands 
of  one  or  two  persons.  For  the  purposes  of  the  dentist,  however, 
it  will  be  sufficient  to  fix  the  draw-plate  securely  between  the  jaws 
of  a  bench-vise,  and,  by  seizing  hold  of  one  end  of  the  gold  rod 
with  a  strong  pair  of  clamps  or  flat-nosed  pliers,  serrated  or  cut 
like  a  file  on  the  inside  of  the  jaws,  the  wire  may  be  drawn  stead- 


FlG.    46. 


ily  through  the  plate,  passing  from  the  larger  to  the  smaller  holes 
until  a  wire  of  the  required  size  is  obtained. 

In  drawing  the  wire,  the  motion  should  be  steady  and  uniform, 
for  if  drawn  interruptedly  or  by  jerks,  the  wire  will  be  marked  by 
corresponding  inequalities.  The  gold  rod  should  also  be  annealed 
from  time  to  time,  and  the  holes  kept  well  greased  or  waxed. 

The  process  described  above  will  answer  equally  well  in  reduc- 
ing any  of  the  ductile  metals  to  wire,  as  silver,  copper,  platinum, 
etc.,  so  that  any  further  description  of  the  method,  in  connection 
with  these  metals,  will  be  unnecessary. 

Method  of  Constructing  Spiral  Springs.  —  Inasmuch  as  spiral 
springs  have  been,  to  a  great  extent,  superseded  by  more  ap- 
proved agencies  employed  in  the  retention  of  artificial  teeth  in 


FORMING   GOLD   ALLOYS    FOR   DENTAL    USE. 


97 


the  mouth,  and  as  all  the  principal  dental  furnishing  houses  are 
supplied  with  these  appliances  already  prepared  for  use,  it  does 
not  seem  necessary  to  enter  into  a  description  of  the  various  ap- 
paratus used  in  making  them. 

The  following  simple  contrivance  will  meet  the  limited  require- 
ments of  those  who  are  obliged  or  prefer  to  manufacture  their 
own  springs.  The  wire,  obtained  as  already  described,  by  means 
of  the  draw-plate,  is  held  between  two  blocks  of  wood  fastened 
between  the  jaws  of  a  bench-vise,  as  shown  in  Fig.  46.  By  means 
of  a  small  hand-vise,  one  end  of  the  wire  is  clamped  to  a  uniformly 
cylindrical  and  well-tempered  steel  rod  or  wire,  four  or  six  inches 
long,  and  about  the  size  of  a  small  knitting-needle,  and  which 
being  made  to  revolve  while  resting  on  the  blocks  of  wood,  the 
wire  is  wound  firmly  and  compactly  around  it,  producing  a  uni- 
form coil. 


CHAPTER  VII. 

SILVER. 

Ag  (Aigentum). 

General  Properties  of  Silver. — Pure  silver,  when  planished, 
is  the  brightest  of  the  metals.  Fused,  or  in  the  form  of  ingot,  its 
specific  gravity  is  10.47;  Dut  when  hammered  or  condensed  in  the 
coining  press,  its  density  is  increased  and  its  specific  gravity  be- 
comes 10.6.  It  is  very  malleable  and  ductile,  yielding  leaves 
not  more  than  j-q-^-qqq  of  an  inch  thick,  and  wire  400  feet  of 
which  may  be  drawn  weighing  but  a  single  grain.  It  exceeds 
gold  in  tenacity  or  cohesion,  but  is  inferior  to  platinum  in  this  re- 
spect. A  silver  wire  .078  of  an  inch  in  diameter  will  sustain  a 
weight  of  187.13  pounds.  Fine  silver  is  unaffected  by  moisture  or 
pure  atmospheric  air,  but  is  readily  tarnished  with  a  film  of  brown 
sulphuret  by  exposure  to  sulphureted  hydrogen.  The  sulphuret 
of  silver  thus  formed  may  be  easily  removed  by  rubbing  the 
metal  with  a  solution  of  chameleon  mineral,  prepared  by  calcining 
equal  parts  of  black  or  peroxid  of  manganese  and  niter.  Unlike 
gold  and  platinum,  it  is  readily  soluble  in  nitric  acid,  this  and  sul- 
phuric acid  being  the  only  simple  ones  that  dissolve  it. 

Silver  fuses  at  an  extreme  red  heat,  generally  estimated  at 
1873 °  F.  It  becomes  very  brilliant  when  heated ;  boils  and  vapor- 
izes above  its  fusing-point ;  and  when  cooled  slowly  its  surface 
presents  a  crystalline  appearance. 

Alloys  of  Silver.  —  Silver  combines  readily  with  most  metals, 
forming  compounds  of  variable  degrees  of  malleability,  ductility, 
density,  etc. 

Tin,  zinc,  antimony,  lead,  bismuth,  and  arsenic  render  it  brittle. 
A  very  minute  quantity  of  tin  is  fatal  to  the  ductility  of  silver. 
.Silver  does  not  easily  combine  with  iron,  although  the  two  metals 
may  be  united  by  fusion.  Gold,  copper,  platinum,  iridium,  steel, 
manganese,  and  mercury  also  form  alloys  with  silver. 

An  alloy  of  nine  parts  of  silver  and  one  part  of  copper  is  the 

98 


SILVER.  99 

Government  standard  of  the  United  States  coinage  since  1837.  To 
this,  three-cent  pieces  form  an  exception ;  these  being  composed 
of  three  parts  silver  and  two  of  copper.  The  coins  of  silver  hav- 
ing a  greater  average  fineness  than  those  of  our  own  country  are 
Brazil,  Britain,  Chili,  France,  Greece,  Hindustan,  Persia,  Portu- 
gal, Rome,  and  Tuscany.  A  common  impression  prevails  that  the 
Mexican  silver  coin  contains  more  than  an  average  percentage  of 
pure  silver,  and  it  is  therefore  sought  after  on  account  of  its  sup- 
posed purity.  This  is  true  of  some  pieces  coined  at  different 
periods,  but  the  average  fineness  of  the  Mexican,  as  well  as  the 
Spanish  coins,  falls  below  that  of  the  United  States  mints. 

Refining  Alloys  of  Silver. — The  following  accounts  of  the  man- 
ner of  obtaining  pure,  or  nearly  pure,  silver  from  alloys  of  that 
metal  by  the  dry,  and  wet  or  humid  methods,  are  given  by  Prof. 
Essig  in  his  treatise  on  "'  Dental  Metallurgy :  " 

"  Dry  Method. — The  dry  method  or  assaying  process  consists 
in  forming  an  alloy  of  the  silver  with  lead,  and  is  especially  appli- 
cable to  ores  and  the  sweepings  of  the  dentist's  laboratory.  The 
specimen  to  be  treated  is  heated  with  from  twelve  to  thirty  times 
its  weight  of  granulated  lead,  in  a  bone-ash  cupel,  which  is  placed 
in  a  muffle  so  arranged  that  a  current  of  atmospheric  air  may  pass 
freely  over  the  vessel  and  oxidize  the  lead.  This  oxid  of  lead, 
being  quite  fusible,  combines  with  any  base  metal  present  and 
oxidizes  it,  uniting  subsequently  with  the  oxid  as  a  fusible  slag, 
while  the  gold  or  silver  will  be  held  by  the  unoxidized  portion  of 
the  lead.  In  the  treatment  of  specimens  of  alloy,  such  as  plate 
or  coins,  a  quantity  of  the  specimen  is  accurately  weighed  and 
mixed  with  from  four  to  five  times  its  weight  of  pure  granulated 
lead.  It  is  then  placed  in  the  cupel  and  exposed  to  heat,  as  above 
described,  until  all  the  lead  is  oxidized  or  converted  into  litharge, 
when  the  remaining  button  assumes  the  brilliant  apearance  of 
surface  to  which  allusion  has  been  previously  made,  denoting  that 
the  base  metals  or  oxidizable  constituents  have  been  oxidized  and 
taken  up  by  the  lead  oxid.  This  button  is  then  to  be  weighed  by 
means  of  a  delicate  assay  balance,  and  the  loss  of  weight  denotes 
the  amount  of  alloy  that  was  present. 

"Wet  Method.  —  Pure  silver,  which  is  reckoned  as  1000  fine, 
may  be  obtained  from  standard  or  other  grades  of  silver  by  dis- 
solving them  in  nitric  acid  slightly  diluted  with  water,  the  solution 


IOO  MECHANICAL   DENTISTRY. 

being  much  facilitated  by  exposure  to  gentle  heat.  If  gold  be 
associated  with  the  alloy  it  will  be  found  at  the  bottom  of  the 
vessel,  in  which  case  it  will  be  necessary  to.  use  a  siphon  to  re- 
move the  argentic  nitrate  solution.  The  silver  is  now  to  be 
precipitated  in  the  form  of  chlorid  by  the  addition  of  an  excess 
of  common  salt.  When  all  has  subsided,  the  liquid  is  carefully 
poured  off,  and  the  chlorid  thoroughly  washed,  to  remove  all 
traces  of  acid.  The  chlorid  is  then  placed  in  water  acidulated 
with  hydrochloric  acid  (an  ounce  of  chlorid  requiring  six  to  eight 
ounces  of  water)  and  pieces  of  clean  wrought-iron  put  in  it,  when 
a  copious  evolution  of  hydrogen  follows,  which,  uniting  with  the 
chlorin  of  the  argentic  chlorid,  liberates  metallic  silver.  The 
latter  should  not  be  disturbed  until  the  last  particle  of  it  is  thus 
reduced,  when  it  will  be  found  to  be  a  spongy  mass.  The  un- 
dissolved iron  should  now  be  carefully  removed,  the  ferrous  and 
ferric  chlorid  carefully  decanted,  and  the  silver  washed  in  hot 
water  containing  about  one-tenth  its  bulk  of  hydrochloric  acid. 
This  is  repeated  several  times,  and  finally  the  silver  is  again  thor- 
oughly washed  with  pure  hot  water.  The  silver,  after  drying,  is 
then  ready  for  melting,  and  if  care  has  been  observed  in  the  proc- 
ess it  will  be  found  to  be  of  a  fineness  of  999.7  parts  in  1000,  the 
0.3  of  impurity  present  being  due  to  traces  of  iron.  The  chlorids 
may  be  acidulated  with  sulphuric  acid,  and  reduced  with  zinc  in- 
stead of  iron. 

"  Another  method  of  precipitating  silver  in  the  metallic  form 
consists  in  placing  a  sheet  of  copper  in  a  solution  of  argentic 
nitrate.  The  metal  is  thrown  down  in  a  crystalline  form.  Silver 
thus  obtained  is  never  free  from  traces  of  copper. 

"  Pure  silver  can  only  be  obtained  from  samples  of  a  lower 
grade  by  fusing  the  pure  chlorid  with  sodium  carbonate.  The  re- 
action is  shown  in  the  following  equation : 

sAgCl  +  Na2C03  =  Ag2  +  sNaCl  +  O  +  C02. 

Owing  to  the  copious  evolution  of  carbonic  acid  gas  which  takes 
place  during  the  decomposition,  some  of  the  silver  may  be  thrown 
from  the  crucible,  and  loss  may  occur  by  the  absorption  by  the 
crucible  of  some  of  the  fused  chlorid.  To  avoid  this,  the  sides  of 
the  vessel  should  be  coated  with  a  hot  saturated  solution  of  borax. 
"  A  composition  of  100  parts  of  argentic  chlorid,  70.4  of  calcic 


SILVER.  IOt 

carbonate  (chalk),  and  4.02  of  charcoal,  has  been  recommended 
as  a  means  of  obtaining  pure  silver.  This  mixture  is  heated  to 
dull  redness  for  thirty  minutes,  and  then  raised  to  full  redness ; 
carbonic  acid  and  carbonic  oxid  are  given  off;  the  calcic  chlorid  is 
converted  into  calcic  oxychlorid,  underneath  which,  in  the  bottom 
of  the  crucible,  will  be  found  the  button  of  pure  silver." 

Reduction  of  Silver  to  the  Required  Forms  for  Dental  Pur- 
poses.—  Owing  to  the  very  soft  and  flexible  nature  of  silver  in  its 
pure  state,  it  is  usual,  when  converting  it  into  plate  or  other  forms 
for  use,  to  employ  an  alloy  of  the  metal.  Hence  silver  coins, 
which  are  made  harder  by  the  copper  they  contain,  are  generally 
selected  for  the  purpose.  The  employment  of  silver,  thus  de- 
based, as  a  base  for  dental  substitutes  is  regarded  by  many  as 
unsafe  and  injudicious.  Although  the  influences  of  an  alloy  so 
readily  acted  upon  as  this  by  the  various  agents  which  affect  it 
chemically  cannot  always  be  certainly  predicted  in  every  case,  yet 
no  reasonable  doubt  can  be  entertained  but  that,  under  the  favor- 
ing conditions  which  usually  exist  in  the  mouth,  the  evils  accru- 
ing, directly  and  indirectly,  to  the  organs  of  the  mouth,  and 
through  them  to  the  general  system,  are  positive  and  undoubted. 
If  used  at  all,  therefore,  it  should  be  alloyed  with  the  least  prac- 
ticable amount  of  copper,  or,  what  is  better,  pure  silver  should  be 
reduced  with  platinum  alone,  in  sufficient  quantities  to  impart  to 
the  plate  an  adequate  degree  of  strength  and  elasticity.  The  ten- 
dency of  silver  to  tarnish  in  the  mouth  when  alloyed  with  copper 
may  be  diminished  by  boiling  the  finished  piece  in  a  solution  of 
cream  of  tartar  and  chlorid  of  soda,  or  common  salt,  or  by  scrub- 
bing it  with  aqua  ammonia,  which  removes  the  superficial  par- 
ticles of  copper  and  exposes  a  surface  of  fine  silver.  When  plati- 
num is  introduced  as  the  sole  alloying  component,  the  purity  of 
the  silver  is  not  only  preserved,  but  the  alloy  is  less  easily  acted 
on  chemically,  while  the  plate  derived  from  it  is  rendered  suffi- 
ciently inflexible  and  elastic.  From  three  to  five  grains  of  plati- 
num may  be  added  to  one  pennyweight  of  pure  silver. 

On  account  of  the  strong  affinity  of  sulphur  for  silver,  the  fuel 
most  proper  to  be  used  in  melting  it  is  charcoal.  The  various- 
processes  employed  in  the  conversion  of  silver  into  the  required 
forms  for  use  are  similar  to  those  described  for  gold,  and  need  not 
be  recapitulated. 


102  MECHANICAL   DENTISTRY. 

Formulas  for  Silver  Solders.  —  Silver  solders  are  usually  com- 
posed of  silver,  copper,  and  zinc  in  variable  proportions.  Alloys 
formed  from  the  following  formulas  are  such  as  are  generally 
employed  in  soldering  silver  plate,  derived  from  the  coins  of  that 
metal.  Three-cent  pieces,  composed  of  two  parts  silver  and  one 
of  copper,  may  be  used  for  the  same  purpose : 

Formula  No.  i.  Formula  No.  2. 

Silver, 66  parts.  Silver,   6  parts. 

Copper,   30      "  Copper,   2      " 

Zinc,   10      "  Brass,    1  part. 

When  the  material  to  be  united  is  composed  of  pure  silver  and 
platinum,  silver  coin  alloyed  with  one-tenth  zinc  may  be  used  as 
a  solder. 

In  compounding  silver  solders  the  silver  and  copper  should  be 
first  melted,  and  the  zinc  or  brass  afterward  added,  when  they 
should  be  quickly  poured,  to  prevent  undue  waste  by  oxidation  of 
the  more  fusible  component.  The  ingot,  when  cold,  should  be 
rolled  into  a  plate  a  little  thicker  than  that  recommended  for  gold 
solder. 


CHAPTER  VIII. 

PLATINUM. 
Pt. 

General  Properties. — Platinum  is  a  grayish- white  metal,  re- 
sembling, in  some  measure,  polished  steel.  It  is  harder  than 
silver,  and  has  a  density  greater  than  any  other  known  metal,  its 
specific  gravity  being  21.25.  It  remains  unaltered  in  the  highest 
heat  of  a  smith's  forge,  and  can  only  be  fused  by  means  of  the 
oxyhydrogen  blowpipe  and  galvanism.  A  white  heat  does  not 
tarnish  it,  nor  is  it  in  any  way  affected  by  exposure,  either  in  the 
air  or  water.  It  is  insoluble  in  any  of  the  simple  acids ;  nitro- 
muriatic  acid  (aqua  regia)  being  the  only  one  that  dissolves  it.  It  is 
sufficiently  malleable  to  be  hammered  into  leaves  so  thin  as  to  be 
blown  about  by  the  breath.  It  may  be  drawn  into  wire  yinnr 
of  an  inch  in  diameter,  and  a  still  greater  attenuation  may  be 
obtained  by  coating  the  wire  with  silver,  drawing  it  out,  and 
dissolving  off  the  latter  metal.  It  expands  less  by  heat  than 
any  other  metal,  and  is  much  inferior  to  gold,  silver,  and  copper 
as  a  conductor  of  electricity.  While  it  does  not  oxidize  in  the  air 
at  any  temperature,  nor  is  soluble  in  any  one  acid,  if  heated  to  red- 
ness in  the  air,  in  contact  with  caustic  alkalies  or  alkaline  earths, 
a  hydrated  oxid  is  formed  which  combines  with  the  alkaline  base 
in  a  similar  manner  to  palladium. 

Platinum,  when  absolutely  pure,  is  quite  soft  and  flexible,  and 
when  rolled  into  thin  sheets,  say  28  or  30  of  the  gage  plate,  and 
well  annealed  at  a  strong  white  heat  for  eight  or  ten  minutes,  it  may 
be  readily  forced  into  all  the  inequalities  of  a  zinc  die  without 
producing  any  appreciable  change  in  the  face  of  the  latter. 

The  fusing-point  of  platinum  is  above  35000  F.,  to  reach  which, 
in  the  laboratory,  it  is  necessary  to  employ  the  oxyhydrogen 
blowpipe  or  electric  current. 

The  following  interesting  and  practical  observations  on  the 
method  of  melting  platinum  scraps  are   by   E.   A.   L.   Roberts. 

103 


104  MECHANICAL   DENTISTRY. 

By  the  process  of  welding,  the  operator  will  be  enabled  to  recon- 
vert his  waste  scraps  of  platinum  into  convenient  forms  for  use, 
and  of  which  he  could  not  otherwise  avail  himself,  on  account  of 
the  infusible  nature  of  this  metal  in  its  uncombined  state : 

"  Platinum  used  by  dentists  should  be  soft,  tough,  and  without 
flaws.  These  qualities  can  be  attained  only  by  thorough  melting 
and  welding.  The  welding  must  be  done  at  a  white  heat. 
When  the  surface  is  cool  enough  to  be  visible,  the  metal  is  too 
cool  to  be  welded,  and  every  blow  is  injurious,  because  it  has  a 
tendency  to  shatter  and  shake  it  to  pieces.  The  necessary  deli- 
cacy of  this  process  and  the  uncertainty  of  success  has  led  some 
writers  to  declare  that  platinum  is  incapable  of  being  welded. 
The  platinum  must  be  perfectly  clean,  and  must  be  heated  in  a 
muffle.  When  welded,  the  metal  should  be  handled  with  tongs 
plated  with  platinum,  and  hammered  with  a  clean  hammer  on  a 
clean  anvil,  both  of  which  should  be  as  hot  as  possible  without 
drawing  the  temper  of  the  steel.  The  hammer  used  in  welding 
should  weigh  about  a  pound,  to  prevent  drawing  the  metal ;  but 
when  welded  the  metal  may  be  forged  with  a  heavier  hammer. 

"  The  scraps  or  sponge  should  be  condensed  in  a  square  mold, 
very  compactly,  two  pieces  of  which,  weighing  from  10  to  20 
ounces,  may  be  put  in  a  muffle  together.  When  the  heat  becomes 
so  great  that  on  opening  the  door  the  metal  becomes  invisible, 
bring  one  of  the  pieces,  in  the  tongs,  quickly  to  the  anvil,  give  it 
three  or  four  quick,  sharp  blows,  in  rapid  succession.  Return  the 
piece  to  the  muffle,  and  proceed  with  the  other  piece  in  like  man- 
ner, and  thus  alternately  until  both  are  thoroughly  welded. 

"  Platinum  should  never  be  thrown  into  water  while  hot,  as 
that  tends  to  make  it  crystallize.  It  should  be  thoroughly  ham- 
mered, which  makes  it  tough  and  fibrous. 

"  The  following  process  gives  the  best  results  in  melting  this 
metal.  Condense  the  scraps,  sponge,  or  filings  in  an  iron  mold. 
Lay  the  condensed  mass  on  a  concave  fire-brick,  and  heat  it  to 
whiteness.  Take  the  brick  from  the  muffle,  and  place  it  in  a 
sheet-iron  pan,  coated  with  plaster  and  asbestos.  The  pan  should 
be  deep  enough  and  broad  enough  to  catch  all  globules  and  other 
loose  particles  of  the  metal.  Place  it  under  the  jet  of  the  oxy- 
hydrogen  blowpipe  in  the  following  manner: 

"  The  pan  is  provided  with  a  handle,  opposite  to  which  is  a  ring, 


PLATINUM.  105 

which  is  to  be  attached  to  an  iron  hook  and  rod,  suspended  from 
the  ceiling  by  a  slip  of  india-rubber,  which  enables  the  operator  to 
hold  the  pan  conveniently  at  any  distance  from  the  jet  of  the  burn- 
ing gases.  The  hydrogen  is  first  lighted,  and  gives  a  powerful 
flame,  but  as  the  oxygen  combines  with  it,  the  flame  subsides  into 
an  intense  focus  of  heat,  in  which  the  metal  is  soon  brought  to  a 
state  of  fusion.  Begin  at  one  end  and  melt  along  toward  the 
other,  till  the  whole  is  fused  in  one  mass.  The  platinum  in  this 
condition,  when  cool,  is  quite  crystallized  and  sonorous.  It  breaks 
very  easily,  like  spelter-zinc.  Heat  it  very  hot  and  forge  it.  A 
continuation  of  this  process  renders  it  soft,  tough,  and  fibrous. 
When  reduced  to  the  width  desired,  and  to  the  thickness  of  ^  °f 
an  inch,  it  should  be  made  very  hot  and  passed  instantly  through 
the  rollers." 

Use  for  Dental  Purposes. — Platinum,  in  mechanical  practice,  is 
chiefly  employed  as  a  base  for  continuous-gum  work ;  as  a  color- 
ing ingredient  of  porcelain ;  for  pins  for  attaching  mineral  teeth ; 
for  backings  and  dowels  in  crown-  and  bridge-work;  and,  to  a 
limited  extent,  in  some  of  the  minor  operations  of  the  laboratory. 

Solder  for  Platinum. — Pure  gold  is  the  only  proper  solder  for 
this  metal. 

Alloys  of  Platinum.  —  Platinum  unites  with  most  of  the  base 
metals,  forming  alloys  of  variable  degrees  of  hardness,  elasticity, 
brittleness,  color,  fusibility,  etc.,  but  their  practical  value  to  the 
dentist  is  not  sufficient  to  justify  a  separate  description  of  their 
properties. 

Alloyed  with  gold  it  forms  a  straw-colored  alloy,  the  shade  de- 
pending on  the  quantity  of  gold  added.  Silver  hardens  it,  the  re- 
sulting alloy  being  unaffected  by  sulphur. 

Platinoid  Metals. — The  platinoid  metals,  palladium,  iridium, 
osmium,  rhodium,  and  ruthenium,  are  native  contaminations,  the 
alloys  of  these  metals  having  a  close  general  resemblance  to 
platinum. 

Among  the  platinoid  metals,  palladium  and  iridium  are  the  only 
ones  that  have  been  used  for  dental  purposes,  and  these  only  to  a 
limited  extent.  Palladium  is  of  a  steel-gray  color,  and  when 
planished,  is  a  brilliant  steel-white  metal,  not  liable  to  tarnish  in 
the  air.  Though  closely  resembling  platinum,  it  may  be  readily 
distinguished  from  the  latter  metal  by  the  following  tests:    (1)  It 


I06  MECHANICAL   DENTISTRY. 

has  little  more  than  one-half  the  density  of  platinum.  (2)  If  a 
piece  of  it  is  heated  to  redness,  it  assumes  a  bronze-blue  shade,  of 
greater  or  less  intensity,  as  it  is  cooled  more  or  less  slowly ;  but  if 
it  is  suddenly  chilled  by  immersing  it  in  cold  water,  it  instantly  re- 
sumes its  original  luster.  (3)  When  a  drop  of  the  tincture  of  io- 
din  is  let  fall  upon  its  surface  and  evaporated  over  the  flame  of  a 
lamp,  a  black  spot  remains,  which  does  not  occur  with  platinum. 
Palladium  melts  at  about  the  heat  required  to  fuse  malleable  iron, 
and  is  the  most  fusible  of  the  platinoid  metals.  It  is  soluble  in 
nitric  acid,  but  its  best  solvent  is  nitrohydrochloric  acid. 

Palladium,  being  very  costly,  and  possessing  no  properties  that 
specially  recommend  it  for  dental  use,  is  but  little  employed  in 
prosthetic  practice. 

Iridium,  though  generally  found  associated  with  platinum,  os- 
mium, and  other  allied  metals,  sometimes  occurs  native  and  nearly 
pure.  Like  platinum,  it  is  very  refractory  when  exposed  to  high 
temperatures,  and  can  only  be  fused  by  the  oxyhydrogen  blowpipe 
or  by  the  heat  of  the  voltaic  current.  An  alloy  of  one-fifth  plat- 
inum and  four-fifths  iridium  has  been  met  with  in  octahedral  crys- 
tals, whiter  than  platinum,  and  of  specific  gravity  22.66.  When 
native  platinum  is  dissolved  in  nitrohydrochloric  acid,  black  scales 
remain  behind,  which  are  composed  of  iridium  and  osmium.  These 
metals  may  then  be  separated  by  one  of  the  methods  in  use,  and 
the  iridium  is  obtained  in  a  gray  metallic  powder,  resembling 
spongy  platinum.  Iridium  is  very  hard,  white,  and  brittle,  and 
has  a  specific  gravity  of  21.15.  None  of  the  acids  attack  the  pure 
metal,  but  when  alloyed  with  platinum  it  is  readily  dissolved  by 
aqua  regia  or  nitrohydrochloric  acid.  If  heated  in  a  finely  divided 
state  in  the  open  air,  iridium  absorbs  oxygen ;  it  is  also  oxidized 
by  niter  and  caustic  potash. 

The  extreme  hardness  and  consequent  rigidity  of  iridium  ren- 
ders it,  in  its  unalloyed  state,  practically  unfit  for  base  plates  on 
account  of  the  great  difficulty  of  swaging  it  into  proper  form. 
This,  however,  may  be  accomplished  in  certain  cases,  as  in  partial 
pieces,  with  the  use  of  zinc  dies  and  counters ;  and  in  these  cases 
it  is  desirable  on  account  of  the  increased  strength  its  property  of 
hardness  imparts  to  the  plate.  It  may  be  used  to  advantage,  how- 
ever, alloyed  with  platinum,  a  small  quantity  imparting  to  the 
latter  increased  stiffness  and  elasticity. 


CHAPTER  IX. 

ALUMINIUM. 
Al. 

Derivation. — Aluminium  is  the  metallic  basis  of  alumina,  the 
latter  being  the  characteristic  ingredient  of  common  clay.  It  is 
only  within  a  comparatively  few  years  that  the  attention  of  chem- 
ists has  been  directed  to  the  production  of  this  metal,  with  a  view 
to  its  general  introduction  into  commerce  and  the  arts.  Prior  to 
the  researches  of  M.  Deville,  who,  under  the  patronage  of  the 
then  Emperor  of  the  French,  commenced  his  researches  in  1854 
for  the  production  of  this  metal  on  a  large  scale,  the  small  quan- 
tities produced,  and  the  corresponding  exorbitant  prices  it  com- 
manded, rendered  it  entirely  unavailable  for  other  purposes  than 
merely  scientific  experiment.  The  improvements  in  the  methods 
of. obtaining  it,  however,  which  have  been  more  recently  intro- 
duced, have  rendered  its  production  more  economical,  and  it  is 
now  supplied  in  much  larger  quantities,  and  at  a  corresponding 
reduction  in  the  cost  of  the  metal.  The  latest  process  for  ex- 
tracting aluminium  is  by  the  electric  current.  The  Pittsburg 
Reduction  Company,  especially,  is  using  this  method  with  much 
success. 

General  Properties.  —  One  of  the  most  striking  properties  of 
aluminium  is  its  extreme  lightness,  its  specific  gravity  being  2.6, 
nearly  that  of  glass,  whilst  that  of  platinum  is  21.5,  gold  19.5, 
copper  8.96,  zinc  7.2,  tin  7.3. 

The  metal  is  very  malleable  and  ductile ;  that  is,  it  can  be 
reduced  to  thin  sheets  or  drawn  into  very  fine  threads.  Its  ten- 
acity, though  superior  to  that  of  silver,  is  less  than  that  of  copper ; 
but  no  very  accurate  experiments  have  been  made  in  this  respect. 

When  pure  it  is  about  as  hard  as  silver,  and  is  about  the  color 
of  new  zinc.  Its  elasticity  is  not  great.  It  files  readily,  and  is 
said  not  to  injure  the  file.  It  conducts  electricity  with  great  facil- 
ity, so  that  it  may  be  considered  as  one  of  the  best  conductors 

107 


IOS  MECHANICAL   DENTISTRY. 

known,  almost  equal  in  this  respect  to  silver,  and  more  than  eight 
times  a  better  conductor  than  iron. 

Fusing-point.  —  Aluminium  melts  at  about  11600  F.  (according 
to  the  latest  experiments),  between  zinc  and  silver.  In  its  chem- 
ical qualities  it  would  seem  to  take  an  intermediate  rank  between 
what  are  termed  the  noble  metals  and  the  common  metals,  being, 
as  Deville  states,  one  of  the  most  unalterable  of  metals. 

Corrodibility.  —  One  of  the  most  marked  qualities  of  aluminium 
is  its  resistance  to  oxidation.  It  might  be  imagined  that  it  would 
as  readily  reassume  its  oxygen  as  it  parted  with  it  with  difficulty 
when  in  its  state  of  oxid.  This,  however,  is  not  the  case ;  it  ap- 
pears to  be  as  indifferent  to  oxygen  as  either  platinum  or  gold. 
In  air  and  in  oxygen  it  undergoes  no  sensible  alteration,  and  it 
even  resists  it  at  the  highest  temperature  which  Deville  could  pro- 
duce in  a  cupelling  furnace,  a  temperature  higher  than  that  em- 
ployed in  assaying  gold.  Water  has  no  action,  according  to 
Deville,  on  aluminium,  either  at  its  ordinary  temperature,  when 
boiling,  nor  even  upon  the  metal  at  a  low,  red  heat,  near  its  melt- 
ing-point. According  to  Professor  Crace  Calvert,  this  statement 
must  be  received  with  some  degree  of  caution,  as  in  experiments 
he  has  made  he  considers  that  oxidation  does  take  place  slowly 
when  the  metal  is  immersed  in  water  for  any  considerable  length 
of  time.  It  is  not,  however,  affected  by  sulphur  or  sulphureted 
hydrogen. 

Solubility. — Aluminium  is  not  acted  upon  to  any  considerable 
degree  by  any  of  the  oxyacids  in  the  cold ;  nitric  acid,  whether 
strong  or  weak,  at  its  ordinary  temperature,  in  no  way  affects 
it,  though  when  boiling  it  acts  upon  it  slowly.  Small  grains  of 
aluminium,  plunged  in  sulphuric  acid  for  three  months,  remained 
apparently  unaltered.  The  vegetable  acids,  such  as  acetic,  oxalic, 
and  tartaric  acids,  have  scarcely  any  effect  on  it  at  all.  The  true 
solvent  of  the  metal  is  hydrochloric  acid,  which  attacks  it  rapidly.  It 
appears  to  resemble  tin  when  brought  into  contact  with  hydro- 
chloric acid  and  the  chlorids.  Its  absolute  harmlessness  permits 
of  its  being  employed  in  a  vast  number  of  cases  where  the  use  of 
tin  would  not  be  desirable  on  account  of  the  extreme  facility  with 
which  that  metal  is  dissolved  in  the  organic  acids. 

Manner  of  Annealing.  —  For  the  purpose  of  annealing  alumin- 
ium the  surface  of  the  plate  may  be  coated  with  oil,  and  then 


ALUMINIUM.  IO9 

passed  over  the  flame  of  a  spirit-lamp  or  Bunsen  burner  until  the 
oil  is  entirely  burned  off  and  the  plate  becomes  white,  when  it  is 
instantly  withdrawn.  Or  it  may  be  accomplished  by  placing  the 
piece  of  plate  in  a  furnace  muffle,  an  even  heat  being  maintained 
until  the  metal  is  hot  enough  to  char  the  end  of  a  pine  stick,  which 
should  leave  a  black  mark  behind  it  as  it  is  drawn  over  the  plate. 
The  metal  on  being  withdrawn  should  be  allowed  to  cool  slowly. 

Manner  of  Melting. — Aluminium  should  be  melted  in  ordinary 
plumbago  crucibles,  as  it  does  not  absorb  or  unite  with  carbon 
when  heating  in  contact  with  it.  No  flux  is  needed  to  cover  the 
molten  metal,  as  it  is  non-volatile  at  any  temperature  that  can  be 
obtained  with  an  ordinary  furnace. 

Casting. — Aluminium  is  now  being  used  to  considerable  extent 
in  castings  of  all  descriptions  where  lightness,  non-corrodibility, 
and  silvery  color  is  desired.  Either  iron,  sand,  or  plaster  and 
marble-dust  molds  can  be  used,  the  metal  being  poured  as  cold 
as  possible. 

Polishing. — The  truly  distinctive  and  beautiful  color  of  alumin- 
ium is  best  brought  out  in  highly  polished  plate.  To  polish,  use 
rouge  or  tripoli ;  or  "  Almeta  Polish,"  which  was  introduced  by 
the  Pittsburg  Reduction  Co.,  has  earned  a  well-merited  reputation 
as  an  aluminium  polish.     Its  formula  is  as  follows : 

Stearic  Acid, 1  part. 

Fuller's  Earth 1      " 

Rotten  Stone,    .* 6  parts. 

The  whole  ground  very  fine  and  well  mixed. 

On  flat  surfaces  the  highest  finish  can  be  given  with  fine  emery 
paper  and  oil. 

Soldering. — Several  methods  of  soldering  aluminium  have 
proven  more  or  less  successful  for  some  purposes ;  one  of  the 
solders  is  6  parts  aluminium,  4  copper,  and  90  zinc,  another,  rec- 
ommended by  Schlosser,  is  30  parts  gold,  1  platinum,  20  silver, 
100  aluminium ;  none  of  them,  however,  is  suitable  for  attaching 
•artificial  teeth  to  be  worn  in  the  mouth.  The  only  way  in  which 
the  metal  has  been  successfully  employed  as  a  dental  base  is  with 
the  rubber  attachment. 

Alloys. — Aluminium,  like  iron,  does  not  unite  with  mercury, 
and  scarcely  at  all  with  lead.  It,  however,  forms  a  variety  of 
alloys  with  other  metals.     It  can  be  alloyed  with  iron,  and  seems 


IIO  MECHANICAL   DENTISTRY. 

to  unite  readily  with  zinc ;  a  variety  of  alloys  with  nickel  have 
been  made,  and  that  consisting  of  ioo  parts  of  aluminium  and 
three  of  nickel  is  found  to  work  readily,  and  to  have  gained  hard- 
ness and  rigidity,  as  compared  with  the  pure  metal.  The  alloys,, 
however,  with  copper  are  the  most  striking ;  they  are  light  and 
very  hard,  and  capable  of  a  fine  polish.  In  the  same  degree  that 
copper  adds  to  the  hardness  of  aluminium,  so  does  the  latter,, 
when  used  in  small  quantities,  give  hardness  to  copper,  without,, 
however,  injuring  its  malleability.  It  renders  it  susceptible  of  a 
fine  polish,  and,  according  as  the  proportions  are  varied,  the  color 
of  the  alloy  becomes  deep  or  pale  gold.  Alloys  of  copper  with 
five  and  ten  per  cent,  of  aluminium  resemble  gold,  perhaps,  more 
than  any  other  metallic  alloy  hitherto  employed.  They  do  not 
tarnish  sensibly  by  exposure  to  the  air.  Aluminium  can  be  de- 
posited by  the  battery,  and  by  the  same  agent  it  can  be  gilt  or 
silvered. 

Dental  Uses.  —  For  several  years  past  attempts  have  been  made 
to  render  aluminium  available  as  a  base  for  artificial  dentures, 
both  by  the  swaging  and  casting  processes,  with  only  partial  suc- 
cess. When  in  the  form  of  plate  no  suitable  solder  has  yet  been 
discovered  by  which  the  several  parts  of  a  dental  appliance  may 
be  securely  united,  and  experiments  in  casting  have  not  yet  prov- 
en entirely  satisfactory.  It  is  being  used  to  a  limited  extent,  with 
rubber  attachment,  and  it  is  hoped  that  in  the  near  future,  upon 
further  acquaintance  with  its  capabilities,  it  may  prove  entirely 
acceptable  for  dental  purposes. 


CHAPTER  X. 

COPPER,  ZINC,   LEAD,  TIN,   ANTIMONY,   AND   BISMUTH. 
COPPER. 

Cu  (Cuprum). 

General  Properties.  —  Copper  is  one  of  the  metals  most 
anciently  known ;  it  is  of  a  brownish-red  color,  with  a  tinge  of 
yellow ;  has  a  faint  but  nauseous  and  disagreeable  taste,  and  im- 
parts, when  exposed  to  friction,  a  smell  somewhat  similar  to  its 
taste.  Its  specific  gravity  ranges  from  8.8  to  8.9.  It  is  both 
malleable  and  ductile,  but  excels  in  the  former  property,  finer 
leaves  being  obtained  from  it  than  wire.  It  is  inferior  to  iron  in 
tenacity,  but  surpasses  gold,  silver,  and  platinum  in  this  respect. 
The  fusing-point  of  copper  is  about  20000  F. 

Alloys  of  Copper. — Copper  unites  readily  with  most  metals, 
forming  alloys  of  great  practical  value  in  the  arts,  but  which  have 
but  a  limited  application  in  dental  laboratory  processes.  Many 
of  these  alloys  are  curious  and  instructive,  as  illustrating  the 
singular  and  unaccountable  influence  of  alloying  upon  the  dis- 
tinctive properties  of  the  component  metals.  Copper  and  tin,  for 
example — the  former  of  which  is  highly  ductile,  and  the  latter 
equally  malleable — when  combined  in  the  proportion  to  form 
speculum  metal  (9  C:  1  T),  form  an  alloy  distinguished  for  its  ex- 
treme brittleness,  with  a  surface  hardness  almost  equal  to  steel. 
By  increasing  the  quantity  of  tin  until  the  compound  assumes  the 
proportions  constituting  gun-metal  (C  2:  T  1),  the  alloy,  though 
neither  malleable  nor  ductile,  becomes  eminently  tough  and  rigid. 
Other  prominent  examples  might  be  given,  showing  how  com- 
pletely this  combining  influence  defies  all  calculations  in  regard 
to  ultimate  results.  The  following  summary  embraces  the  names 
and  composition  of  the  more  familiar  alloys  of  copper,  omitting, 
as  unnecessary  in  this  connection,  a  description  of  their  individual 
properties. 

Alloys  of  Copper  with  Zinc. — Brass  is  an  alloy  of  uncertain 

in 


112  MECHANICAL   DENTISTRY. 

and  variable  composition,  consisting  usually,  however,  of  two  to 
five  parts  of  copper  and  one  of  zinc.  Brass  melts  at  18690  F. 
Prince's  metal,  and  its  allied  compounds,  Pinchbeck,  Similor,  and 
Mannheim  gold,  consists  of  nearly  equal  parts  of  copper  and  zinc. 
Mosaic  gold,  consists  of  100  parts  of  copper  and  from  52  to  55  of 
zinc.  Dutch  gold,  from  which  foil  of  that  name  was  formerly  ob- 
tained, is  formed  of  11  parts  of  copper  with  two  of  zinc.  Bath 
metal  is  composed  of  32  parts  of  brass  and  nine  of  zinc. 

Brass  solder  consists  of  two  parts  of  brass  and  one  of  zinc,  to 
which  a  little  tin  is  occasionally  added. 

Alloys  of  Copper  with  Tin. — Bell  metal  usually  consists  of 
100  parts  of  copper  with  from  60  to  63  parts  of  tin.  Cannon 
metal  is  compounded  of  90  parts  of  copper  with  ten  of  tin. 
Cymbals  and  gongs  contain  100  parts  of  copper  and  25  of  tin. 
Speculum  metal  consists  of  two  parts  of  copper  and  one  of  tin. 

Copper  and  arsenic  form  a  white-colored  alloy,  which,  in  the 
proportion  of  nine  parts  of  copper  and  one  of  arsenic,  is  white, 
slightly  ductile,  and  is  denser  and  more  fusible  than  copper. 

German  silver  is  composed  of  copper,  40.4;  nickel,  31.6;  zinc, 
25.4;  iron,  2.6;  but  the  proportions  of  the  metals  of  this  alloy 
differ  according  to  the  various  uses  to  which  this  compound  is 
applied. 

Babbitt  metal  is  a  compound  of  copper,  antimony,  and  tin,  in 
somewhat  varying  proportions.  The  following  formula  is  given  by 
Henry  Long  Jacob  in  the  British  Journal  of  Dental  Science: 

Copper,    2  parts. 

Antimony,    3 

Tin,    12      " 

The  following  method  of  preparing  it  is  given  by  the  same 
writer: 

"  In  preparing  this  metal,  the  copper  is  first  melted  in  a  cruci- 
ble, with  about  an  equal  weight  of  tin  (the  copper  thus  fusing 
much  more  readily  than  by  itself),  a  little  more  of  the  tin  is  then 
added,  next  the  antimony,  and  lastly  the  remainder  of  the  tin  by 
degrees,  stirring  well  during  the  whole  of  the  time ;  the  metal  can 
then  be  poured  into  sand  molds  of  any  convenient  form.  About 
a  year  and  a  half  ago  I  furnished  Mr.  Thomas  Fletcher  with  this 
formula,  and  I  believe  it  is  given  in  his  work  on  '  Dental  Metal- 


ZINC.  II3 

lurgy.'  The  melting-point  of  this  metal  is  lower  than  that  of  zinc 
and  somewhat  higher  than  that  of  lead,  so  that  counter-molds  of 
this  latter  can  be  readily  made  to  it  with  proper  care.  I  am  un- 
der the  impression  that  the  original  Babbitt  metal  was  said  to 
contain  a  portion  of  lead,  but  this  addition  was  found  to  be  injuri- 
ous." 

ZINC. 
Zn  (Zincum). 

General  Properties. — Zinc  is  a  bluish-white  metal,  possessing 
considerable  luster  when  broken.  The  commercial  variety  is 
always  impure,  containing  traces  of  iron,  lead,  cadmium,  arsenic, 
carbon,  etc.  It  does  not  easily  tarnish  in  dry  air,  but  soon  be- 
comes dull  on  exposure  to  moisture.  In  the  condition  in  which 
it  ordinarily  occurs  it  is  a  brittle  metal,  but  may  be  rendered 
malleable  by  annealing  it  at  certain  temperatures.  This  change 
in  its  condition  is  effected  by  subjecting  it  to  a  heat  of  from  2200 
to  3000  F.,  at  which  temperature  it  may  be  rolled  into  sheets,  and 
retain  its  malleability  when  cold.  The  best  annealing  tempera- 
ture for  zinc  is  about  245 °  F.  A  knowledge  of  this  fact  will 
enable  the  operator  to  avail  himself  of  the  advantages  of  this 
property  by  annealing  his  zinc  die,  by  which  its  liability  to  crack 
or  part  under  the  hammer  is  diminished. 

The  fusing-point  of  zinc  is  about  775  °  F.,  and  when  heated 
much  above  this  point  in  contact  with  air,  it  burns  with  a  bril- 
liant, greenish-white  flame,  while  woolly-looking  flocculi  rise 
from  the  vessel  in  which  it  is  being  heated  and  float  in  the  air. 
The  specific  gravity  of  zinc  varies  from  6.9  to  7.2. 

Use  for  Dental  Purposes. — Zinc  has  been  long,  and  almost  ex- 
clusively, employed  in  the  formation  of  dies  used  in  swaging 
metallic  plates  employed  in  mounting  artificial  teeth,  and  experi- 
ence has  very  justly  accorded  to  it  undisputed  preeminence  above 
all  other  unalloyed  metals  for  the  purpose.  A  more  particular 
account  of  its  peculiar  fitness  for  dental  purposes  will  be  given 
under  the  head  of  Metallic  Dies  and  Counter-Dies. 


114  MECHANICAL   DENTISTRY. 


LEAD. 

Pb  (Plumbum). 


Properties. — Lead  has  a  grayish-blue  color,  with  a  bright 
metallic  luster  when  melted  or  newly  cut,  but  it  soon  becomes 
tarnished  and  dull-colored  when  exposed  to  the  air.  The  specific 
gravity  of  commercial  lead,  which  is  usually  contaminated  with 
other  metals,  is  11.352. 

The  fusing-point  of  lead  is  61 70  F.  Exposed  to  a  high  heat, 
it  absorbs  oxygen  rapidly,  forming  on  its  surface  a  gray  film  of 
protoxid  and  metallic  lead.  It  is  both  malleable  and  ductile,  but 
soft  and  perfectly  inelastic. 

Its  Use  in  the  Laboratory. — Lead,  either  in  its  pure  state  or 
when  alloyed  with  certain  other  metals,  serves  important  pur- 
poses in  the  dental  laboratory.  In  its  simple  or  uncombined  state 
it  is  useful  only  in  forming  counter-dies.  Alloyed  with  antimony 
in  the  proportion  of  ^4  to  ^  of  the  latter,  with  the  addition  some- 
times of  very  small  portions  of  copper,  tin,  and  bismuth,  it  forms 
different  grades  of  type-metal,  which  is  harder  than  lead  and  very 
brittle,  and  is  sometimes  used  for  dies ;  and  sometimes,  though 
very  rarely,  for  counter-dies.  When  type-metal  is  used  as  a  coun- 
ter to  a  zinc  die,  it  is  improved  for  the  purpose  by  adding  to  it  an 
equal  quantity  of  lead ;  it  may  also  be  used  in  the  form  of  a  die  in 
connection  with  a  lead  counter  after  rough  stamping  with  zinc. 

Fusible  Alloys. — The  alloy  known  as  Rose's  fusible  metal  is 
composed  of  two  parts  of  bismuth  to  one  of  lead  and  one  of  tin, 
and  melts  at  about  2000  F.  A  still  more  fusible  alloy  is  com- 
posed of  lead  three  parts,  tin  two  parts,  and  bismuth  five  parts, 
which  fuses  at  1970.  There  are  other  alloys  of  lead,  to  be  men- 
tioned hereafter,  melting  at  from  2000  to  4400,  which  may  be 
advantageously  employed  in  forming  dies  to  be  used  after  zinc, 
where  the  latter,  from  its  greater  shrinkage,  fails  to  bring  the 
plate  into  accurate  adaptation  to  the  mouth. 

Soft  solder  is  an  alloy  composed  of  lead  and  tin  in  the  propor- 
tion of  two  parts  of  the  former  to  one  of  the  latter. 


TIN ANTIMONY. 


TIN. 
Sn  (Stannum). 


115 


Properties. — Tin  is  a  brilliant,  silver-white  metal,  the  luster  of 
which  is  not  sensibly  affected  by  exposure  to  the  air,  but  is  easily 
oxidized  by  heat.  It  has  a  slightly  disagreeable  taste,  and  emits, 
when  rubbed,  a  peculiar  odor.  It  is  soft,  inelastic,  and,  when 
bent,  emits  a  peculiar  cracking  sound  called  the  creaking  of  tin. 
It  is  inferior  in  tenacity  and  ductility,  but  is  very  malleable,  and 
may  be  beaten  into  leaves  awg-  °f  an  incn  m  thickness,  ordinary 
tin  foil  being  about  y-^Vs"  of  an  inch  thick. 

The  fusing-point  of  tin  is  about  4500  F. ;  it  boils  at  a  white 
heat,  and  burns  with  a  blue  flame  to  binoxid. 

The  more  common  alloys  of  tin  with  other  metals  have  already 
been  noticed.  It  was  at  one  time  used  as  a  base  for  artificial 
teeth,  and  more  recently  it  has  been  introduced  as  a  component 
of  "  cheoplastic  "  metal,  a  compound  used  for  the  same  purpose. 
In  its  pure  state,  it  is  sometimes  used  for  counter-dies,  and  occa- 
sionally for  dies.  When  employed  for  the  latter  purpose  in  con- 
nection with  a  lead  counter,  the  latter  should  not  be  obtained 
directly  from  the  die,  as  the  high  temperature  of  melted  lead 
would  produce,  when  poured  upon  the  tin,  partial  fusion  of  the 
latter  and  consequent  adhesion  of  the  two  pieces.  Tin  is  also 
used  by  many  operators  as  a  trial  base-plate  for  artificial  den- 
tures, instead  of  wax,  gutta-percha,  or  other  more  pliable  mate- 
rials. 

ANTIMONY. 

Sb  (Stibium). 

General  Properties. — Antimony  is  of  a  silver-white  color,  with 
a  tinge  of  blue,  a  lamellar  texture,  and  a  crystalline  fracture.  It 
is  brittle  and  easily  pulverized.  It  enters  as  an  ingredient  into 
the  composition  of  type-  and  stereotype-metal,  music  plates,  and 
Britannia  metal.  It  is  also  a  component  of  certain  fusible  alloys 
analogous  to  those  already  mentioned  under  the  head  of  lead, 
and  which,  in  the  form  of  a  die,  are  sometimes  used  on  account 
of  their  slight  degree  of  shrinkage. 

The  fusing-point  of  antimony  is  8400  F.,  and  when  heated  at 
the  blowpipe  it  melts  with  great  readiness,  and  diffuses  white 


Il6  MECHANICAL   DENTISTRY. 

vapors,  emitting-  an  odor  similar  to  garlic.     The  specific  gravity 
of  the  purest  variety  is  6.715. 


BISMUTH. 
Bi  (Bismuthum). 

General  Properties.— Bismuth  is  a  white-colored  metal,  resem- 
bling, in  some  degree,  antimony.  It  is  soft,  but  so  brittle  as  to 
be  easily  pulverized.  Its  specific  gravity  is  9.83,  which  may  be 
increased  somewhat  by  hammering. 

The  fusing-point  of  bismuth  is  about  5100  F.  When  the  tem- 
perature of  the  metal  is  raised  from  320  to  2120  it  expands  y^- 
in  length. 

Alloyed  with  Other  Metals. — Bismuth  has  the  property,  in  a 
high  degree,  of  increasing  the  fusibility  of  the  metals  with  which 
it  is  incorporated,  and  is  a  common  ingredient  of  the  more  fusible 
alloys,  some  of  which  melt  in  boiling  water.  One  part  of  bismuth 
with  24  of  tin  is  malleable,  but  the  alloy  of  these  metals  becomes 
brittle  by  the  addition  of  more  bismuth.  Bismuth  unites  readily 
with  antimony,  and  in  the  proportion  of  one  part  or  more  of  the 
former  to  two  of  the  latter,  it  expands  in  the  act  of  cooling. 

There  are  many  other  metals  and  alloys  beside  those  already 
enumerated,  but  which  have  not  been  particularly  described  on 
account  of  their  inutility  in  the  laboratory  for  dental  purposes. 
Among  these  may  be  mentioned  iron,  brass,  bronze,  etc.,  which  are 
only  employed  for  auxiliary  purposes,  and  are  both  inconvenient 
and  impracticable  for  dies  by  reason  of  their  infusible  nature  and 
consequent  contraction ;  nickel,  on  account,  also,  of  its  extreme 
infusibility  and  its  tendency  to  render  the  alloy  of  which  it  is  a 
component  less  fusible ;  sodium,  on  account  of  the  changes  pro- 
duced on  it  by  exposure  to  the  air ;  potassium,  on  account  of  its 
extreme  sensitiveness  to  the  influence  of  low  temperatures,  being 
semi-fluid  at  6o°  F.,  nearly  liquid  at  92°,  and  entirely  so  at 
1200;  arsenic,  because  it  volatilizes  before  fusing;  cadmium,  with 
no  advantages  above  tin,  on  account  of  its  scarcity,  costliness, 
etc. 


CHAPTER  XI. 

GENERAL   PROPERTIES    OF   ALLOYS,   AND    THEIR   TREATMENT   AND 
BEHAVIOR  IN  THE  PROCESS  OF  COMPOUNDING. 

All  alloys  possess  metallic  luster,  are  opaque,  conduct  heat  and 
electricity,  and,  in  a  greater  or  less  degree,  are  ductile,  malleable, 
elastic,  and  sonorous.  Some  alloys,  as  brass  and  gong  metal,  are 
usually  malleable  in  the  cold  and  brittle  when  hot. 

Metals  sometimes  unite  in  atomic  ratios,  forming  compounds 
of  definite  or  equivalent  proportions  of  the  component  metals,  as 
certain  alloys  of  copper  and  zinc,  gold  and  copper,  gold  and  silver, 
mercurial  alloys,  etc.,  while,  on  the  other  hand,  many  are  formed 
in  all  proportions,  like  mixtures  of  salt  and  water. 

Metals  differ  in  respect  to  their  affinity  for  each  other,  and  do 
not,  therefore,  alloy  with  equal  facility ;  thus  it  is  difficult  to  unite 
silver  and  iron,  but  the  former  combines  readily  with  gold,  cop- 
per, or  lead. 

The  ductility  of  an  alloy  is,  in  general,  less  than  that  of  its 
constituent  metals,  and  this  difference  is,  in  some  instances,  re- 
markably prominent,  as  in  the  case  of  certain  alloys  of  copper 
and  tin,  already  mentioned. 

An  alloy  is  generally  harder  than  the  mean  hardness  of  its 
components,  a  property  which,  when  taken  in  connection  with 
their  increased  fusibility,  gives  to  alloys  peculiar  value  in  the  for- 
mation of  dies  for  stamping  purposes.  To  the  rule  stated,  amal- 
gams, or  mercurial  alloys,  are  cited  as  exceptions. 

The  density  of  an  alloy  varies  with  the  peculiar  metals  com- 
posing it,  being  generally  either  greater  or  less  than  the  mean 
density  of  its  several  components. 

It  is  impossible  to  predict  with  certainty  the  melting-point  of 
an  alloy  from  that  of  its  separate  constituents,  but,  generally,  the 
fusibility  of  the  alloy  is  increased,  sometimes  in  a  most  remark- 
able degree.  The  alloy  of  five  parts  of  bismuth,  three  of  lead, 
and  two  of  tin  is  a  striking  example  of  this  fact,  this  compound 
melting  at  1970,  while  the  mean  melting-point  of  its  constituents 

117 


Il8  MECHANICAL   DENTISTRY. 

is  5140.  Silver  solder  is  also  a  familiar  illustration  of  the  influ- 
ence of  alloying  on  the  fusibility  of  metals ;  copper,  melting  at 
19960,  and  silver  at  18730,  when  combined  fuse  at  a  heat  much 
below  that  required  to  melt  silver,  the  more  fusible  component  of 
the  alloy.  Again,  iron,  which  melts  at  a  little  less  than  30000, 
acquires  almost  the  fusibility  of  gold  when  alloyed  with  the  lat- 
ter. Examples  might  be  multiplied,  but  it  will  be  sufficient  to 
add  that,  in  general,  metallic  alloys  melt  at  a  lower  heat  than  is 
required  to  fuse  the  most  refractory  or  infusible  component,  and 
sometimes  lower  than  the  most  fusible  ingredient. 

The  color  of  an  alloy  cannot,  in  general,  be  inferred  from  that 
of  its  component  metals ;  thus  it  would  be  conjectured  that  copper 
would  be  rendered  very  much  paler  by  adding  to  it  zinc  in  con- 
siderable quantities,  but  the  fallacy  of  such  an  inference  is  at  once 
shown  by  an  examination  of  some  of  the  rich-looking  gold-colored 
varieties  of  brass,  as  Prince's  metal,  pinchbeck,  and  similor,  com- 
posed each  of  nearly  equal  parts  of  copper  and  zinc ;  and  Mann- 
heim gold,  compounded  of  three  parts  copper  and  one  of  zinc. 

The  affinity  of  an  alloy  for  oxygen  is  greater  than  that  of  the 
separate  metals,  a  phenomenon  that  is  ascribed  by  Ure  to  the 
increase  of  affinity  for  oxygen  which  results  from  the  tendency  of 
one  of  the  oxids  to  combine  with  the  other ;  by  others  it  is  attrib- 
uted to  galvanic  action.  According  to  Faraday,  100  parts  of  steel 
alloyed  with  one  of  platinum  is  dissolved  with  effervescence  in 
dilute  sulphuric  acid  too  weak  to  act  with  perceptible  energy  on 
common  steel.  It  is  offered  in  explanation  of  this  fact  that  the 
steel  js  rendered  positive  by  the  presence  of  platinum.  A  similar 
illustration  is  afforded  by  the  action  of  dilute  acid  on  commercial 
zinc,  which  is  usually  an  alloy  of  zinc  with  other  metals. 

The  action  of  air  is,  in  general,  less  on  alloys  than  on  the  sepa- 
rate metals  composing  them.  To  this,  however,  there  are  excep- 
tions, as  the  alloy  of  three  parts  of  lead  and  one  of  tin,  which, 
when  heated  to  redness,  burns  briskly  into  a  red  oxid. 

Some  points  of  practical  interest  suggest  themselves  in  connec- 
tion with  the  behavior  and  proper  management  of  alloys  in  the 
process  of  compounding. 

As  metallic  alloys  can  only  be  formed  by  fusion,  and  as  the 
affinity  of  the  metals  composing  them  for  oxygen  is  greatly  in- 
creased by  heat,  especially  those  denominated  base,  it  is  important 


PROPERTIES    AND   TREATMENT   OF   ALLOYS. 


II9 


that  this  tendency,  which  is  incompatible  with  the  proportional 
accurateness  of  the  compound,  should  be,  as  far  as  practicable, 
guarded  against.  Hence,  various  substances  having  a  greater 
affinity  for  oxygen  than  the  metals  to  be  united,  as  oil  or  grease, 
rosin,  powdered  charcoal,  etc.,  are  generally  added,  coating  the 
surface  of  the  liquid  metals,  and  which,  by  affording  a  protective 
covering,  preserve,  with  little  change,  the  proportions  of  the  alloy. 

The  Difficulty  of  Securing  a  Homogeneous  Alloy,  Owing  to  the 
Difference  in  the  Specific  Gravities  of  the  Metals  Composing  It. — 
Some  difficulty  is  occasionally  experienced  in  obtaining  a  per- 
fectly uniform  alloy,  on  account  of  the  different  specific  gravities 
of  the  metals  composing  it — each  metal  assuming  the  level  due 
to  its  density.  This  partial  separation  is  common  to  gold  and  sil- 
ver, provided  they  have  not  been  adequately  stirred  before  pour- 
ing. This  result  is  not  so  likely  to  occur  when  the  metals  em- 
ployed are  in  small  quantities,  and  are  suddenly  cooled,  but  when 
used  in  considerable  masses  and  allowed  to  cool  slowly,  it  is 
much  favored  by  permitting  the  metals  to  fix  themselves  in  the 
order  of  their  separate  densities.  Hence,  whenever  a  notable  dif- 
ference in  the  specific  gravity  of  the  metals  exists,  the  fused  mass 
should  be  briskly  stirred  immediately  before  the  instant  of  pour- 
ing it,  and  should  be  made  to  solidify  quickly.  If  uniformity  be 
not  obtained  in  this  manner,  it  will  be  necessary  to  remelt,  and 
repeat  the  process  until  the  alloy  is  rendered  sufficiently  homo- 
geneous. 

The  Metals  that  Should  be  Melted  First. — In  alloying  three  or 
more  metals  differing  greatly  in  fusibility,  or  that  have  but  little 
affinity  for  each  other,  it  is  better  to  first  unite  those  which  most 
readily  combine,  and  afterward,  these  with  the  remaining  metal 
or  metals.  If,  for  example,  it  is  desired  to  unite  a  small  quantity 
of  lead  with  brass  or  bronze,  some  difficulty  would  be  experienced 
in  forming  the  alloy  by  direct  incorporation  of  the  metals,  but 
union  could  be  readily  effected  by  first  melting  the  lead  with  zinc 
or  tin,  and  then  adding  the  melted  copper. 


CHAPTER  XII. 

TREATMENT  OF  THE  MOUTH  PREPARATORY  TO  THE  INSERTION  OF 
ARTIFICIAL  DENTURES. 

It  rarely  occurs  that  all  the  structures  of  the  mouth  are  in  such 
condition  as  will  render  it  proper  to  insert  an  artificial  appliance 
without  some  preparatory  treatment.  This  important  require- 
ment cannot,  in  any  material  respect,  be  disregarded  by  the  prac- 
titioner without  endangering  the  utility  and  permanence  of  the 
substitute,  and  inflicting  upon  the  patient  a  train  of  consequences 
alike  distressing  and  pernicious.  Every  experienced  dentist  is 
familiar  with  the  fact  that  an  artificial  substitute,  resting  upon 
diseased  roots  of  teeth  and  impinging  continually  upon  gums  al- 
ready irritated  and  inflamed,  soon  becomes  a  source  not  only  of 
annoyance  and  discomfort  to  the  patient,  but  is  rendered,  in  a 
great  degree,  inefficient  in  the  performance  of  some  of  its  more 
important  offices.  There  is,  besides,  a  perpetual  and  cumulative 
aggravation  of  the  morbid  conditions,  and  sooner  or  later  irre- 
trievable destruction  of  the  remaining  natural  organs  will  be  in- 
duced. These  consequences  cannot  be  wholly  averted  by  the 
most  skilful  manipulation,  but  they  may  be  greatly  magnified  by 
a  defective  execution  of  the  work,  or  by  a  faulty  adaptation  of  the 
appliance  to  the  parts  in  the  mouth. 

Patients  not  infrequently  attempt,  by  every  artifice  or  pretext 
that  caprice  or  timidity  may  suggest,  to  persuade  the  operator  to 
violate  his  own  clear  convictions  of  duty,  but,  unless  under  cir- 
cumstances of  peculiar  exigency,  he  should  be  careful-  to  guard 
himself  against  the  imputation  of  incompetency  or  bad  faith  by 
being  peremptory  and  unyielding  in  his  demands  upon  the  patient 
to  submit  to  the  necessities  and  just  requirements  of  the  case, 
and  no  ordinary  circumstance  should  influence  him  in  opposition 
to  his  better  informed  judgment. 

The  conditions  usually  met  with,  to  which  it  will  be  necessary 
to  direct  attention  in  the  treatment  of  the  mouth,  arc:  (i)  The 
presence  of  useless  and  diseased  remains  of  teeth.     (2)  Accumula- 

120 


PREPARATORY    TREATMENT    OF   THE    MOUTH.  121 

tions  of  tartar.  (3)  Diseased  states  of  the  gums  and  mucous 
membrane.     (4)  Caries. 

Useless  and  Diseased  Remains  of  Teeth. — It  may  be  stated, 
as  an  absolute  rule  of  practice,  that  all  teeth,  or  remains  of  teeth, 
affected  by  incurable  forms  of  disease,  should  be  removed  before 
inserting  either  partial  or  entire  dentures.  This  recommendation 
must,  however,  be  construed  in  the  light  of  the  curative  resources 
of  dental  surgery  and  therapeutics.  Many  diseased  conditions 
associated  with  the  teeth  that  have  heretofore  been  generally  re- 
garded as  incurable,  have,  in  the  use  of  more  radical  and  efficient 
remedial  measures,  proven  amenable  to  such  treatment  as  assures 
their  retention  for  many  years  in  a  condition  fitting  them  for  im- 
portant uses.  A  new  impulse  has  of  late  been  given  to  such  con- 
servative treatment  of  these  organs  with  the  view,  chiefly,  of 
utilizing  them  more  generally  for  purposes  of  support  in  setting 
artificial  crowns,  and  in  the  method  of  replacement  known  as 
"  bridge-work." 

The  marked  success  which  of  late  years  has  attended  the  treat- 
ment of  diseased  roots,  and  the  increasing  importance  attached  to 
them  for  the  purposes  mentioned,  as  well  also  as  the  essential 
office  they  perform  in  preserving  the  structural  integrity  of  the 
associated  alveoli,  and  in  maintaining  the  normal  circulation  and 
nutrition  of  the  parts,  would  seem  to  justify  the  conclusion  that 
their  extraction  is  plainly  contraindicated,  save  in  rare  and  excep- 
tional cases  of  intractable  disease,  in  which  case  there  is  no  ques- 
tion concerning  the  propriety  or  necessity  of  their  removal. 
Their  presence  in  connection  with  the  substitute  must,  sooner  or 
later,  become  not  only  a  source  of  annoyance  and  distress  to  the 
patient,  but  will,  in  all  probability,  lead  ultimately  to  conse- 
quences of  a  still  graver  nature.  Inflammation  and  suppuration 
will  be  likely  to  be  induced,  or,  if  already  present,  will  be  aggra- 
vated by  the  mobility  and  unaccustomed  pressure  of  the  substi- 
tute in  the  process  of  mastication,  thus  contaminating  and  vitiat- 
ing the  oral  secretions,  which  act,  by  reason  thereof,  with  increas- 
ing energy  upon  oxidizable  materials  present  in  the  mouth,  as 
well  as  upon  the  remaining  natural  teeth,  while  the  contiguous 
parts,  through  their  immediate  connection  or  sympathetic  rela- 
tions with  the  structures  of  the  mouth,  respond  to  the  local  dis- 
turbances, and  the  case,  in  time,  becomes  complicated  with  those 


122  MECHANICAL    DENTISTRY. 

various  distressing  maladies  about  the  head  and  face  so  commonly 
associated  with  diseased  conditions  of  the  oral  cavity.  At  last, 
the  patient,  no  longer  able  to  endure  the  offensiveness  and  dis- 
tress arising  from  the  presence  of  the  substitute  in  the  mouth,  or 
to  properly  masticate  his  food,  is  compelled  to  have  the  offending 
organs  removed.  The  absorption  of  the  gums  and  processes 
which  follows  this  operation,  and  the  corresponding  changes 
which  occur  therefrom  in  the  form  of  the  alveolar  ridge,  make  it 
imperative  either  to  reconstruct  the  piece  or  to  supply  the  patient 
with  an  entirely  new  substitute ;  whereas,  if  due  regard  had  been 
given  to  the  proper  preparation  of  the  mouth  in  the  first  instance, 
the  patient  might  be  spared  such  inflictions,  and  the  operator  the 
discredit  which  almost  invariably  attaches  to  the  neglect  of  the 
measures  recommended. 

Removal  of  Salivary  Calculus  or  Tartar. — The  deposits  of  tar- 
tar which  so  frequently  collect  at  the  necks  of  the  teeth  and  under 
the  free  margins  of  the  gum  are  a  prolific  source  of  evil,  inducing 
ultimate  destruction  of  the  investing  membranes  and  contiguous 
alveoli,  and  as  this  deposit  is  continuous  and  progressive,  follow- 
ing closely  the  wasting  or  destruction  of  the  implicated  tissue, 
teeth  originally  firm  become  in  time  not  only  unfitted  for  the 
proper  performance  of  the  functions  required  of  them,  but  a 
source  of  diseased  action  in  surrounding  structures.  Hence  it 
becomes  absolutely  necessary,  as  it  relates  to  the  general  health 
of  the  mouth,  to  thoroughly  remove,  with  suitable  instruments, 
all  traces  of  this  concretion  from  the  teeth.  In  some  complica- 
tions characterized  by  suppurating  processes  and  necrosed  alve- 
oli, as  in  so-called  "  Rigg's  disease,"  or  pyorrhea  alveolaris,  the 
treatment  must  be  more  thorough  and  radical. 

Diseased  Conditions  of  the  Mucous  Membrane  and  Gums. — 
It  will  seldom  be  necessary  to  institute  treatment  for  the  reduc- 
tion of  inflammation  and  suppuration  of  the  soft  tissues  of  the 
mouth  after  removal  of  diseased  roots  and  tartar,  inasmuch  as 
these  conditions,  being  generally  provoked  by  and  associated  with 
the  latter,  will  spontaneously  subside  with  the  removal  of  the 
exciting  causes.  If,  however,  this  does  not  occur  within  a  rea- 
sonable time,  relief  may  generally  be  obtained  with  the  use,  as  a 
mouth-wash,  of  any  of  the  remedies  ordinarily  employed,  as 
dilute  tincture  of  arnica,  myrrh,  or  calendula,  phenol  sodique,  etc. 


PREPARATORY    TREATMENT    OF    THE    MOUTH.  1 23 

As  a  means  of  allaying  soreness  or  tenderness  of  the  gums  after 
extraction,  the  writer  has  had  gratifying  success  in  the  use  of 
Electrozone,  or  Pond's  extract  of  hamamelis.  If  there  are  mor- 
bid conditions  of  the  soft  tissues  or  osseous  structures  of  the 
mouth,  not  immediately  arising  from  the  presence  of  diseased 
roots  and  tartar,  they  should  be  treated  in  accordance  with  the 
particular  pathological  conditions  present. 

Caries  or  Decay  of  the  Remaining  Teeth. — In  order  that  all  the 
teeth  which  it  is  deemed  advisable  to  retain  in  the  mouth  may 
be  permanently  preserved,  it  will  be  necessary  to  fill,  or  other- 
wise treat,  such  as  may  be  affected  by  caries.  This  operation 
will  be  attended  with  more  satisfactory  results,  and  be  accom- 
panied with  less  pain  to  the  patient  and  diminished  risk  of  failure, 
when  performed  after  the  removal  of  the  roots  of  teeth  and  tartar, 
and  the  restoration  of  diseased  conditions  of  the  mouth  to  health, 
as,  in  this  case,  there  will  be  less  irritability  of  the  general  system 
and  reduced  sensitiveness  of  the  teeth  operated  on. 

Surgical  Treatment  of  the  Mouth  After  the  Extraction  of 
Teeth. — In  the  operation  of  extracting  preparatory  to  the  inser- 
tion of  artificial  dentures,  especially  in  cases  accompanied  by 
unavoidable  fracture  of  the  processes,  it  sometimes  happens  that 
loose  and  pendulous  portions  of  gum  remain,  giving  temporary 
annoyance  to  the  patient.  Any  considerable  excess  of  such  tissue 
may  be,  in  part  at  least,  clipped  off,  while  sharp  and  protruding 
portions  of  processes  at  other  points  should  be  removed,  for,  if 
allowed  to  remain,  the  gum  closing  over  them  will,  in  a  short 
time,  become  irritated  and  inflamed,  and  exceedingly  painful  to 
the  slightest  pressure.  If,  in  the  course  of  a  few  weeks,  promi- 
nences still  remain,  over  which  the  mucous  membrane  is  stretched 
and  irritated  or  inflamed,  as  is  more  frequently  the  case  around 
the  sockets  of  the  cuspid  teeth,  the  membrane  should  be  divided 
over  such  points  with  a  lancet,  and  the  sharp  points  of  bone  un- 
derneath broken  down  with  suitable  cutting  instruments.  This 
condition,  however,  can  usually  be  obviated,  in  a  measure,  by 
firmly  pressing  the  process  together  immediately  after  extraction. 

Time  Necessary  to  Elapse  After  the  Extraction  of  Teeth 
Before  Inserting  Artificial  Dentures. — The  time  that  should 
elapse  after  extracting  the  natural  teeth,  before  replacing  them 
with    artificial    substitutes,    will    depend    upon    various    circum- 


124  MECHANICAL    DENTISTRY. 

stances.  If  the  appliance  is  only  intended  to  meet  the  wants  of 
the  individual  until  all  the  changes  effected  by  absorption  of  the 
gums  and  processes  are  fully  completed,  it  may  be  inserted  in 
from  one  to  three  weeks,  depending  somewhat  upon  the  number 
of  teeth  extracted,  the  extent  of  the  injuries  unavoidably  inflicted 
upon  the  parts,  and  the  virulence  of  the  diseased  action  present 
in  the  structures  of  the  mouh  at  the  time  of  the  operation.  If 
there  are  no  unusual  complications,  and  the  space  or  spaces  to  be 
supplied  are  such  as  are  made  by  the  loss  of  only  one  or  two  teeth 
at  intervals,  the  parts  quickly  assume  their  normal  condition,  and 
the  piece  to  be  temporarily  worn  may  be  applied  within  a  few 
days.  If,  however,  a  greater  number,  or  all  of  the  teeth  have 
been  removed,  more  or  less  inflammation  and  tenderness  will  be 
present  for  from  ten  days  to  two  or  three  weeks,  rendering  the 
wearing  of  an  artificial  piece  uncomfortable  to  the  patient,  and  in 
some  degree  mischievous,  by  aggravating  the  morbid  conditions 
already  existing.  Another  objection  to  the  too  early  introduc- 
tion of  artificial  substitutes  into  the  mouth  arises  from  the  fact 
that  the  changes  which  occur  in  the  ridge  are  much  more  rapid 
within  the  first  few  weeks  after  the  extraction  of  the  teeth  than  at 
any  subsequent  period,  so  that  the  plate,  if  inserted  immediately 
or  within  a  few  days  after  such  an  operation,  will  soon  lose  its 
bearing  upon  the  ridge  and  become  inefficient  for  masticating 
purposes,  or  may  even  fail  to  be  retained  in  the  mouth  without 
much  annoyance  to  the  patient.  From  two  to  eight  or  more 
weeks  should,  therefore,  elapse  before  inserting  the  substitute. 
In  the  meantime,  the  patient  should  be  seen  frequently,  and  such 
medical  or  surgical  treatment  adopted  from  time  to  time  as  the 
case  may  demand. 

The  time  occupied  in  the  completion  of  those  changes  which 
occur  in  the  alveolar  border  after  the  extraction  of  all  or  any  con- 
siderable number  of  the  teeth  cannot  be  definitely  stated,  but  will 
range  from  five  to  twelve  months  or  more,  according  to  the 
amount  of  superfluous  structures  to  be  removed,  the  density  of 
the  osseous  tissues,  and  the  functional  activity  of  the  absorbents. 
In  all  cases,  ample  time  should  be  permitted  to  elapse  in  order 
that  no  appreciable  change  in  the  form  of  the  parts  may  take  place 
after  the  appliance  has  been  permanently  adjusted.  It  should  be 
remembered,  however,  that  there  is  no  period  of  time  when  the 


PREPARATORY   TREATMENT    OF    THE    MOUTH.  125 

changes  in  the  maxillary  bones  which  follow  the  extraction  of  the 
natural  teeth  may  be  said  to  be  absolutely  completed.  It  is  well 
known  that,  in  exceptional  cases,  renewed  absorption  may  occur 
long  after  the  time  when  it  is  supposed  to  be  completed,  extend- 
ing in  some  cases  quite  beyond  the  ordinary  limits.  This  is 
ascribed  by  many  to  misfitting  plates,  or  to  some  particular  qual- 
ity of  the  material  used  as  a  base,  notably  vulcanized  rubber. 
While  there  may  be  some  plausibility  in  this  view,  it  can  hardly 
be  accepted  as  final  or  conclusive.  That  the  unusual  destruction 
or  wasting  away  of  involved  tissue  is  induced  by  some  abnormal 
action  of  the  absorbent  or  nutritive  processes  is  without  ques- 
tion, but  whether  this  is  induced  by  local  or  systemic  causes  re- 
mains in  doubt. 


CHAPTER  XIII. 

MATERIALS,    APPLIANCES,   AND    METHODS   EMPLOYED   IN    OBTAIN- 
ING IMPRESSIONS  OF  THE  MOUTH. 

In  the  process  of  constructing  a  dental  substitute,  it  is  of  the 
first  importance  that  as  accurate  an  impression  as  possible  should 
be  obtained  of  all  those  parts  of  the  mouth  with  which  the  appli- 
ance is  in  any  way  connected.  If  this  important  preliminary  step  is- 
in  any  essential  respect  imperfectly  performed,  the  ultimate  utility  of 
the  artificial  -fixture  will  either  be  greatly  impaired  or  wholly  de- 
stroyed, notwithstanding  all  the  subsequent  manipulations  may 
be  most  carefully  and  skilfully  performed.  The  operator,  there- 
fore, should  not  only  avail  himself  of  every  appliance  and  facility 
that  will  enable  him  to  attain  the  most  perfect  results,  but  should 
have  an  exact  and  intelligent  acquaintance  with  the  nature,  prop- 
erties, and  adaptability  of  the  impression  materials  used. 

The  substances  usually  employed  for  this  purpose  are :  bees- 
wax, modeling  composition,  and  plaster-of-Paris. 

Some  diversity  of  opinion  exists  as  to  the  relative  value  of  these 
several  impression  materials,  and  the  choice  of  any  one  of  the 
class  is  generally  determined  by  individual  notions  of  the  indica- 
tions to  be  fulfilled  in  any  given  case,  and  the  supposed  special 
adaptability  of  the  material  to  the  fulfilment  of  such  indications. 

In  the  case  of  entire  dentures,  where  there  is  a  near  approach  to 
uniformity  of  hardness  or  softness,  and  consequent  uniformity  of 
resistance,  in  the  tissues  of  the  mouth,  plaster,  of  the  proper  con- 
sistency, unquestionably  takes  precedence  of  all  other  materials 
for  the  purpose,  and  the  almost  universal  preference  given  to  it  in 
such  cases  is  a  virtual  confession  of  its  superior  fitness.  Its  capa- 
bility, beyond  that  of  all  the  other  substances  mentioned,  of  secur- 
ing the  most  perfect  impression  of  the  several  parts  in  their  undis- 
turbed relation  to  each  other  is  unquestioned,  and  it  may  be 
affirmed  with  positiveness  that,  except,  possibly,  in  the  case  of 
plastic  bases,  where  there  is  no  compensation  for  the  slight  ex- 
pansion of  the  plaster,  if  all  the  surfaces  on  which  the  substitute 

126 


IMPRESSIONS    OF    THE    MOUTH. 


127 


rests  were  equally  pliant  or  equally  resistant  to  forces  applied  to 
them,  no  other  material  would  be  required.  But,  strictly  speak- 
ing, this  condition  of  uniformity  never  prevails,  and  in  many  cases 
there  is  a  marked  departure  from  it.  The  most  common  and 
troublesome  complication  of  this  kind  occurs  where  there  is  a 
more  or  less  pliable  or  yielding  condition  of  the  alveolar  ridge 
associated  with  a  comparatively  hard  and  resistant  surface  along 
the  median  line  of  the  floor  of  the  palate,  being  more  pronounced 
near  the  soft  palate.  In  such  cases,  this  inequality  of  softness 
and  hardness,  if  considerable,  prevents  a  properly  balanced  con- 
tact and  pressure  of  a  substitute  constructed  from  an  impression 
of  the  parts  in  a  state  of  repose.  Thus,  for  example,  in  the  case 
of  a  perfectly  fitting  denture  secured  in  the  manner  just  stated,  if 
the  ridge  along  the  mesial  line  of  the  palatal  vault  is  more  than 
usually  hard  and  prominent,  and  the  lateral  portion  of  the  arch 
and  alveolar  ridge  relatively  soft  and  yielding,  the  substitute, 
meeting  with  a  fixed  point  of  resistance  at  the  floor  of  the  palate, 
will  prevent  the  lateral  walls  and  ridge  from  being  sufficiently 
compressed  on  the  application  of  retaining  forces,  whether  atmos- 
pheric, adhesive,  or  capillary,  or  all  combined.  Hence,  when 
forcible  pressure  is  made  on  one  side  over  the  ridge,  as  in  masti- 
cation, the  substitute,  impinging  or  riding  upon  the  central  resis- 
tant surface  of  the  arch,  as  upon  a  pivotal  point,  will  be  detached 
and  thrown  off  from  the  opposite  side.  If  the  same  yielding  con- 
dition of  the  anterior  portion  of  the  ridge  prevails,  the  appliance, 
when  forces  are  applied  to  the  front  teeth,  will  be  dislodged  pos- 
teriorly. 

The  proposed  remedy  for  the  instability  of  the  substitute,  re- 
sulting from  the  conditions  mentioned,  consists  in  so  constructing 
the  dental  appliance  that,  when  applied  to  the  mouth  and  sub- 
jected to  the  action  of  the  retaining  forces,  a  degree  of  resistance 
in  those  parts  where  the  soft  tissues  are  in  excess  will,  through 
compression  of  the  tissues,  be  secured,  equal,  or  nearly  so,  to  that 
presented  by  the  central  portion  of  the  arch ;  in  other  words,  by 
establishing  an  equilibrium  of  pressure  or  resistance  in  all  the 
parts  on  which  the  plate  rests. 

It  is  believed  by  some  teachers,  that  certain  forms  of  impres- 
sion material,  through  the  pressure  they  exert,  are  capable  of  con- 
tributing materially  to  this   result.     This  is   predicated   on   the 


128  MECHANICAL    DENTISTRY. 

assumption  that  the  pressure  they  exert  is  sufficient  to  compress 
or  displace  the  tissues  in  question.  The  writer,  however,  thinks 
it  well  to  inquire  if  the  compressing  power  of  these  substances,  in 
the  cases  under  consideration,  has  not  been  overrated.  If  by  the 
term  compression,  as  used  in  this  connection,  is  meant  condensa- 
tion or  diminished  bulk  of  tissue,  certainly  no  such  result  could 
be  obtained  by  any  force  capable  of  being  applied  within  the 
mouth,  however  hard  and  resistant  the  material  used.  Any 
change  in  the  normal  configuration  of  the  arch  and  ridges  possi- 
ble in  the  use  of  such  substances  must,  therefore,  result,  not  in 
condensation,  but  in  displacement  of  tissue.  It  can  be  readily  under- 
stood how  this  displacement  may  occur  along  the  summit  line  of 
the  ridge  in  cases  characterized  by  considerable  excess  of  gum 
material  lying  in  loose  and  gristly  folds,  chiefly  in  front  of  the 
bicuspids,  and  associated  generally  with  the  long  use  of  partial 
dentures.  In  applying  pressure  in  such  cases,  the  effect  would  be 
to  force  these  mobile  structures  out  of  their  customary  relations 
to  the  ridge  and  arch.  How  far  such  a  procedure  is  in  accordance 
with  the  principles  of  correct  practice  must  be  submitted  to  indi- 
vidual judgment.  That  any  change  in  the  mere  relative  position 
of  such  loose  structures  to  the  ridge  would  contribute  in  any 
appreciable  manner  to  the  stability  of  the  substitute  is  not  very 
apparent. 

Within  the  limits  of  the  maxillary  arch  or  palatal  vault,  the 
fossae  or  depressions  lying  on  either  side  of  the  central  line  are 
filled  more  or  less  completely  with  a  mass  of  comparatively  soft 
but  elastic  areolar,  cellular,  or  connective  tissue,  which,  in  its  un- 
changed condition,  is  thought  practically  to  interfere,  in  many 
cases,  with  a  properly  balanced  contact  or  bearing  of  the  substi- 
tute. A  partial  remedy,  at  least,  it  is  claimed  by  many,  may  be 
found  in  the  use  of  some  impression  material  of  sufficient  firm- 
ness to  compress  or  displace  such  tissues  sufficiently  to  afford 
points  of  resistance  to  the  substitute  equal,  or  nearly  so,  to  that 
offered  by  the  median  line  of  the  arch.  The  displacement  here, 
if  any,  would  be  in  the  direction  of  the  least  resistance,  or  toward 
the  velum  or  soft  palate,  all  portions  of  the  arch  anterior  to  the 
latter,  except  in  the  case  of  an  air-chamber,  offering  effectual  re- 
sistance to  displacement  in  any  other  direction.  When  the  nature 
and  relations  of  these  associated  soft  structures  of  the  mouth  are 


IMPRESSIONS   OF   THE    MOUTH.  120, 

considered,  it  is  highly  improbable,  and  we  think  impossible,  that 
any  appreciable  change  of  contour  within  the  arch  could  take 
place  on  the  application  of  any  force  applied  in  the  use  of  either 
wax  or  modeling  composition.  If  these  conclusions  should  be 
justified  by  experimental  tests,  as  we  believe  they  would  be,  it 
would  be  practically  unimportant,  except  where  the  tissues  of  the 
ridge  are  characterized  by  unusual  mobility,  what  material  was 
used,  provided  a  perfect  impression  could  be  obtained  with  it. 
The  paramount  merits  of  plaster,  as  a  substance  capable  beyond 
question  of  fulfilling  perfectly  this  requirement,  would  therefore 
recommend  it,  in  preference  to  any  other  material ;  and  we  might 
add,  too,  that  the  more  difficulties  there  are  presented  in  securing  an 
accurate  impression,  the  more  reason  there  is  for  using  plaster-of- 
Paris  as  the  impression  material. 

One  possible  result  of  the  use  of  any  of  the  impression  mate- 
rials named,  exclusive  of  plaster,  both  in  full  and  partial  cases, 
must  always  render  their  employment  of  doubtful  expediency 
whenever  plaster  can  be  successfully  manipulated  for  the  same 
purpose,  namely,  their  great  liability  to  distortion  on  the  applica- 
tion of  forces  necessary  to  detach  them  from  the  mouth,  and  the 
impossibility  of  detecting  any  change  of  form  until  the  error,  too 
late  for  correction,  is  revealed  in  a  faulty  adaptation  of  the  finished 
piece  to  the  mouth.  It  must  not,  however,  be  understood  from 
this  that  it  is  impossible  to  secure  a  practically  accurate  impres- 
sion of  the  parts  in  the  use  of  these  materials.  The  purpose  is, 
rather,  to  impress  the  importance  and  absolute  necessity  of  extra- 
ordinary care  in  their  manipulation  in  order  to  secure  satisfactory 
results.  The  relative  liability  of  the  several  substances  named  to 
such  disturbance  of  form,  and  the  precautions  necessary  to  avoid 
such  an  unfortunate  and  generally  fatal  accident,  will  be  more 
particularly  noticed  when  we  come  to  treat  of  them  individually 
as  impression  materials.  This  will  be  done  in  the  order  before 
named. 

Beeswax. — There  are  two  varieties  of  this  substance  in  common 
use,  the  yellow  and  white  wax.  The  more  desirable  properties  of 
the  yellow  wax  are  often  impaired  by  the  admixture  with  it  of 
tallow,  with  which  it  is,  for  mercenary  purposes,  frequently  con- 
taminated. The  presence  of  tallow  may  be  detected  by  its  charac- 
teristic odor,  and  by  the  whitish  or  pale  yellow  color  it  imparts  to 
the  wax,  which  in  its  pure  state  is  of  a  deep,  bright  straw  color. 
9 


13° 


MECHANICAL    DENTISTRY. 


Wax  used  for  impressions  should  always  be  kept  in  convenient 
form  for  immediate  use,  and  may  be  prepared  either  by  warming 
it  until  sufficiently  soft  and  then  rolling  or  pressing  it  into  thin 
sheets ;  or,  having  melted  it  in  a  properly  formed  vessel,  immerse 
in  it  a  strip  of  thin  board,  previously  moistened,  and  withdraw 
quickly ;  this  is  repeated  as  the  successive  layers  cool,  until  a  coat- 
ing of  sufficient  thickness  is  obtained.  The  latter  is  a  convenient 
method  of  obtaining  sheets  of  wax  of  a  uniform  thickness,  a  form 
frequently  required  for  various  purposes  in  the  dental  laboratory. 

The  following  directions  in  the  use  of  wax  will  apply  also  to  its 
combinations  with  paraffin  and  gutta-percha,  and  also  to  model- 
ing compositions. 

Manner  of  Obtaining  an  Impression  of  the  Mouth  in  Wax  for 
Partial  Upper  Dentures. — Until  within  the  past  few  years,  wax 
has  been  used  almost  exclusively  for  the  purpose  of  obtaining  an 
impression  of  the  mouth  in  those  cases  where  any  number  of  the 
natural  teeth  remain  in  either  or  both  jaws;  for  this  purpose  it 
is  ordinarily  more  convenient  and  manageable  than  plaster,  and, 
if  carefully  manipulated,  will  secure  in  many  cases  a  sufficiently 
accurate  impression  of  the  parts. 

Before  preparing  the  wax,  a  suitable  impression-cup  or  tray 
should  be  selected,  conforming  as  nearly  as  possible  in  size  and 
shape  to  the  general  form  of  the  arch  and  ridge.  The  proper  size 
should-  always  be  determined  by  trial  of  the  empty  cup  in  the 
mouth  before  taking  the  impression. 

Impression-cups  are  made  from  a  variety  of  substances,  as 
sheet-tin,  porcelain,  vulcanized  rubber,  and  Britannia  metal,  and 
sometimes,  in  order  to  meet  the  requirements  of  special  or  excep- 
tional cases,  either  brass,  copper,  block-tin,  or  gutta-percha  may 
be  used. 

Cups  constructed  of  sheet-tin,  which  any  tinner  can  readily 
make  to  order,  were  formerly  very  generally  used  for  partial  cases, 
and  if  proper  care  is  taken  not  to  inflict  injury  to  the  lips  and  soft 
parts  with  the  thin,  sharp  edges,  when  introducing  and  pressing 
the  cup  to  its  place  in  the  mouth,  they  may  be  used  with  satisfac- 
tion. 

Porcelain  cups  are  adapted  to  the  use  of  the  several  impression 
materials  named,  except  plaster,  the  latter  being  quite  liable  to 
part  from  their  glazed  surfaces  on  the  application  of  the  necessary 
force  to  detach  the  impression,  leaving  the  plaster  in  the  mouth. 
Aside  from  their  purity  and  attractive  appearance,  they  possess 


IMPRESSIONS    OF   THE    MOUTH. 


131 


no  advantages  that  would  make  them  preferable  to  Britannia 
cups,  while  they  are  objectionable  because  of  their  liability  to  in- 
jury, and  entire  incapability  of  being  changed  in  form  to  meet 
special  requirements.  When  used  in  connection  with  wax,  they 
should  be  slightly  heated  before  the  former  is  introduced. 

Hard-rubber  trays,  of  any  desired  form,  may  be  readily  made 
from  plaster  models  by  any  one  accustomed  to  rubber  work,  and 
are  chiefly  adapted  to  the  use  of  plaster,  as  they  are  not  readily 
cleansed  if  other  than  plastic  substances  are  employed.  Their 
form  may  be  materially  changed  by  immersing  them  for  a  few 
moments  in  boiling  water. 

Britannia  metal,  however,  meets  most  fully  all  the  requirements 
of  an  impression-cup,  and  is  well  adapted  to  the  use  of  any  of  the 
impression  materials  commonly  employed.  The  great  variety  in 
form  and  size  found  at  dental  depots,  will  amply  meet  all  the  re- 

Fig.  47. 


quirements  of  ordinary  cases.  For  unusual  or  abnormal  condi- 
tions requiring  exceptional  forms  of  trays,  the  operator  can  con- 
struct for  himself,  from  these,  such  appliances  as  will  best  serve 
his  purpose  in  the  individual  case. 

The  Form  of  Cup  to  Use. — Whatever  cup  is  selected  in  secur- 
ing an  impression  in  wax  for  a  partial  upper  case,  it  should  be 
large  enough  to  embrace  the  alveolar  ridge,  leaving  a  space  of 
nearly  *4  of  an  inch  between  the  rim  and  the  external  wall  of  the 
alveolar  ridge.  In  partial  upper  cases  requiring  an  impression, 
it  may  be,  of  only  a  limited  portion  of  the  arch,  as  where  clasps 
are  used,  or  of  the  entire  hard  palate,  the  form  of  cup  illustrated 
in  Fig.  47  should  be  employed. 


132 


MECHANICAL    DENTISTRY. 


A  cup  designed  for  similar  cases  by  Dr.  Wardle,  exhibited  in 
Fig.  48,  is  particularly  adapted  to  high  arches,  being  provided 
with  a  movable  palate  plate,  by  which  the  central  portion  of  the 
impression  material  is  effectually  forced  into  the  highest  portions 
of  the  palatal  arch,  and  laterally  against  the  sides  and  necks  of 
the  remaining  teeth.  The  same  result  can  be  accomplished,  how- 
ever, by  using  the  ordinary  impression-cup,  and  building  up  the 
rear  and  center  of  the  palatine  portion  with  softened  beeswax, 
before  introducing  the  plaster. 

Having  selected  a  cup  of  the  proper  form  and  size,  the  wax 
should  be  warmed  over  a  spirit-flame  until  it  acquires  about  the 
consistency  of  freshly-made  putty.  Wax  is  sometimes  softened 
by  immersing  it  in  hot  water,  but  the  dry  heat  is  preferable,  as  the 
former  seems  to  impair,  to  some  extent,  its  toughness  and  con- 
tinuity. 

Fig.  48. 


The  Position  of  the  Operator. — In  taking  the  impression  the 
operator  should  place  himself  behind  and  to  the  right  of  the  pa- 
tient, and  should  be  sufficiently  raised  above  the  latter  to  enable 
him  to  manipulate  with  the  greatest  ease  and  certainty,  and  at 
the  same  time  to  command  as  full  and  unobstructed  a  view  of  the 
interior  of  the  mouth  as  possible. 

Manner  of  Introducing  the  Cup,  etc. — The  cup,  with  the  wax 
arranged  should  then  be  introduced  into  the  mouth  without  un- 
necessary delay.  To  do  this  properly,  and  without  subjecting 
the  patient  to  annoyance,  will  occasionally  require  some  care  and 
expertness,  on  account  of  the  disproportionate  size  of  the  cup  and 
orifice  of  the  mouth.  An  ample  and  expanded  jaw,  for  example, 
is  frequently  associated  with  a  small  mouth,  and  if  in  addition  to 
this  the  sphincter  muscle  of  the  mouth  happens  to  be  rigid  and 


IMPRESSIONS    OF    THE    MOUTH.  1 33 

unyielding,  the  introduction  of  a  cup  of  sufficient  size  may  be 
attended  with  some  difficulty  and  embarrassment.  This  impedi- 
ment, however,  may  be  readily  overcome  in  most  cases  by  pre- 
senting the  cup  obliquely  to  the  mouth,  one  side  resting  against, 
and  pressing  outward,  the  corner  of  the  mouth,  while — as  the 
opposite  corner  is  extended  with  the  first  and  second  fingers  of 
the  left  hand — the  cup  is  passed  in  with  a  rotary  movement. 

When  the  cup  is  within  the  mouth  it  should  be  carefully  ad- 
justed over  the  ridge  before  pressing  it  up,  so  that  no  portion  of 
the  rim  may  cut  into  the  soft  tissues  of  the  mouth,  an  accident  lia- 
ble to  happen  without  care,  and  which  will  make  it  necessary,  in 
most  cases,  to  withdraw  the  cup  before  the  impression  is  com- 
plete. The  proper  position  of  the  cup  in  the  mouth  secured,  it 
should  be  held  firmly  with  the  thumb  resting  on  the  handle  above, 
and  two  or  more  of  the  fingers  on  the  under  surface,  when  it  is 
slowly  but  steadily  and  forcibly  pressed  against  the  parts  above 
until  the  ridge  is  completely  imbedded,  and  the  wax  carried 
closely  against  the  roof  of  the  mouth.  The  cup  should  then  be 
held  stationary  with  two  fingers  from  each  hand;  applying  equal 
pressure  upon  both  sides,  while  with  the  thumbs  the  wax  around 
the  margins  of  the  cup  should  be  pressed  closely  into  all  the 
depressions  occurring  on  the  outside  of  the  ridge  between  the 
remaining  teeth,  or  wherever  irregularities  may  present  them- 
selves on  the  external  border  of  the  jaw. 

After  the  wax  has  remained  in  the  mouth  long  enough  to  be- 
come in  some  degree  hardened,  it  should  be  carefully  detached  by 
gentle  traction  upon  the  cup,  and  removed  from  the  mouth  in  the 
same  manner  in  which  it  was  introduced,  care  being  taken  not  to 
displace  the  wax  or  otherwise  mar  the  impression.  The  force 
with  which  the  wax  impression  will  adhere  to  the  mucous  surfaces 
on  the  complete  exclusion  of  air  is  oftentimes  very  considerable, 
and  will  require  a  corresponding  tractive  force  to  dislodge  it.  In 
applying  this  force,  it  should  be  borne  in  mind  that,  in  the  very 
plastic  condition  in  which  the  wax  is  applied  to  the  mouth,  it  is 
not  only  very  soft  and  yielding,  but,  being  wholly  inelastic,  is  incapa- 
ble of  recovering  its  form  when  temporarily  disturbed,  and  that,  con- 
sequently, any  distortion  of  the  impression  occurring  from  the 
force  applied  in  removing  it  from  the  mouth  will  be  permanent 
and   possibly  fatal.     It  should,   therefore,   as   has   already  been 


134  MECHANICAL   DENTISTRY. 

stated,  be  allowed  to  remain  in  the  mouth  long  enough  to  become 
somewhat  hardened,  say  from  three  to  five  minutes,  and  this  proc- 
ess may  be  facilitated  by  holding  against  the  cup  a  napkin  satur- 
ated with  cold  water.  The  proper  degree  of  hardness  will,  how- 
ever, depend  upon  the  circumstances  of  the  case.  If  the  remain- 
ing teeth  present  to  each  other  parallel  walls,  or  nearly  so,  per- 
mitting an  easy  escape  of  the  wax  from  the  interdental  spaces,  the 
greatest  practicable  degree  of  hardness  that  can  be  obtained  is  de- 
sirable. If,  on  the  other  hand,  these  spaces  are  V-shaped  or  dove- 
tailed, as  is  very  generally  the  case  where  the  teeth  to  be  replaced 
have  been  long  absent,  the  impression  should  be  removed  while 
the  wax  is  somewhat  plastic,  permitting  a  ready  separation  by 
such  displacement  of  wax  immediately  around  the  adjoining  teeth 
as  must  always  occur  in  these  cases  in  the  use  of  wax.  In  propor- 
tion as  the  wax  is  rendered  hard  and  unyielding  will  be  the  resis- 
tance to  its  escape  from  these  spaces,  and  the  danger  of  change 
of  form  in  parts  of  the  impression  more  or  less  remote  from  them 
augmented.  It  is,  therefore,  unadvisable  in  such  cases  to  produce 
hardness  artificially  by  the  application  of  ice  or  cold  water.  Un- 
der similar  conditions,  the  same  precautions  should  be  taken 
against  overhardening  in  the  use  of  modeling  composition. 

Imperfections  occurring  from 'displacement  or  dragging  of  wax 
on  removal  from  the  mouth,  if  inconsiderable,  may  be  remedied 
with  tolerable  accuracy  by  subsequent  carving  of  the  plaster 
model,  and  this  may  be  aided  by  a  comparison  of  the  plaster  rep- 
resentation of  the  teeth  with  those  in  the  mouth.  If,  however, 
the  interdental  undercuts,  and  those  associated  with  bell-crowned 
teeth  at  other  points,  are  more  pronounced,  it  is  better  to  use 
either  the  modeling  composition  or  plaster. 

Inasmuch  as  it  is  necessary,  in  constructing  partial  sets  of  teeth 
where  swaged  base-plates  are  used,  to  be  provided  with  two  or 
more  plaster  models,  and  as  the  latter  cannot  well  be  obtained  in 
perfect  condition  from  a  single  impression,  it  is  better  that  at  least 
two  of  the  latter  should  be  secured  in  the  first  instance. 

Manner  of  Obtaining  an  Impression  of  the  Lower  Jaw  in  Wax, 
for  Partial  Dentures. — If  the  case  is  one  where  teeth  at  intervals 
are  to  be  supplied,  the  form  of  cup  illustrated  in  Fig.  49  may  be 
employed.  If,  however,  as  is  more  generally  the  case,  the  front 
teeth  remain,  and  those  posterior  .to  the  cuspids  or  bicuspids  are 


IMPRESSIONS   OF   THE    MOUTH. 


135 


to  be  replaced,  the  form  of  cup  exhibited  in  Fig.  50  should  be 
used,  a  portion  being  cut  out  from  the  front  part  of  it,  forming  a 
vacuity  which  receives  and  permits  an  unobstructive  passage  of 
the  front  teeth.  As  the  latter  are  often  very  long,  it  is  difficult, 
with  the  ordinary  form  of  cup,  to  press  the  wax  down  fairly  upon 
the  ridge  behind  without  bringing  their  cutting  edges  prema- 
turely in  contact  with  the  floor  of  the  cup  in  front.  Instead  of 
the  opening  represented  in  the  cup,  however,  it  will  be  sufficient 
in  most  cases  to  have  it  formed  with  a  depression  in  front  of  ade- 
quate depth  to  receive  the  points  of  the  anterior  teeth. 

Position  of  Operator. — In  taking  an  impression  of  the  lower 
jaw,  after  having  prepared  and  arranged  the  wax  by  softening  and 
filling  the  groove  of  the  cup  flush  with  the  margins,  the  operator 
may  first  take  a  position  to  the  right  and  back  of  the  patient  and 
introduce  the  cup  into  the  mouth  in  the  manner  heretofore  de- 


Fig.  49. 


Fig.  50. 


scribed,  when  he  may  pass  a  little  to  the  front  of  the  patient,  and, 
having  adjusted  the  cup  properly  over  the  ridge,  he  should  then 
take  his  place  again,  at  the  side  or  back  of  the  patient,  placing  his 
fingers  of  each  hand  under  each  side  of  the  patient's  jaw,  and  the 
thumbs  upon  the  top  of  the  cup ;  then  make  steady  pressure  until 
the  ridge  is  wholly  imbedded.  Before  final  adjustment  of  the 
wax  to  the  ridge,  however,  care  should  be  taken  not  to  enclose  any 
loose  folds  of  membrane  along  the  line  of  junction  between  the 
ridge  and  cheeks,  or  of  loose  tissue  lying  on  the  inside  near  the 
base  of  the  tongue.  To  avoid  the  former,  immediately  before 
final  pressure  is  made,  the  cheek  should  be  distended  and  drawn 
outward  with  the  finger,  first  on  one  side  and  then  on  the  other, 


136 


MECHANICAL   DENTISTRY, 


holding  the  cup,  in  the  meanwhile,  steadily  in  place.  The  loose 
and  movable  tissues  on  the  inside  will  be  drawn  away  from  the 
ridge  somewhat  if  the  patient  is  directed  to  raise  the  tongue  well 
toward  the  roof  of  the  mouth.  Some  little  additional  pressure 
may  then  be  made  upon  the  cup,  after  which  the  wax  should  be 
pressed  in  around  the  margins  of  the  cup,  both  externally  and 
within,  when  the  impression  is  carefully  removed  from  the  mouth, 
observing  the  precautions  stated  when  treating  of  wax  and  other 
allied  substances. 

Manner  of  Obtaining  an  Impression  of  the  Mouth  in  Wax,  for 
Entire  Upper  Dentures. — The  form  of  cup  employed  in  taking  an 
impression  of  the  upper  jaw,  in  the  absence  of  all  the  natural 
teeth,  is  seen  in  Fig.  51.  A  number  of  these  corresponding  as 
nearly  as  possible  in  form  and  size  to  the  various  modifications  in 

the  configuration  and  dimen- 
sions of  the  maxillary  arch, 
should  be  kept  conveniently  at 
hand.  If  the  teeth  have  been 
recently  extracted,  the  wax 
should  be  prepared  somewhat 
softer  than  usual,  to  prevent 
displacement  of  the  gums, 
which,  in  their  unabsorbed  con- 
dition, possess  more  or  less  mo- 
bility. The  cup  should  be  filled 
flush  with  the  edges,  and  built 
up  in  the  center  if  the  depth 
of  the  palatal  vault  requires  it, 
and  the  wax  properly  trimmed;  it  is  then  introduced  into  the 
mouth  and  adjusted  to  the  ridge,  as  already  described,  and 
pressed  to  the  jaw  with  sufficient  force  to  fully  encase  all  the 
parts  to  which  the  substitute  is  ultimately  to  be  applied.  The 
wax,  as  the  cup  is  pressed  up,  has  a  tendency  to  roll  out  at  its 
edges,  and  thus  depart  from  the  upper  and  outer  portions  of  the 
ridge ;  hence  care  must  be  taken  to  press  the  wax  in  around  the 
marginal  portions  of  the  cup,  as  has  previously  been  directed,  fill- 
ing up  any  depressions  or  fossae  that  may  occur  on  the  external 
border  of  the  jaw.  It  is  particularly  necessary  to  observe  this 
precaution  whenever  the  ridge  overhangs,  as  is  prominently  the 
case  for  the  first  few  months  after  the  extraction  of  the  teeth. 


IMPRESSIONS    OF   THE    MOUTH. 


137 


Fig.  52. 


If  the  impression  is  an  accurate  one,  some  difficulty  is  occa- 
sionally experienced  in  detaching  it  from  the  mouth,  on  account 
of  the  thorough  exclusion  of  air  from  between  it  and  the  mouth 
the  wax  being  held  firmly  in  place  by  adhesive  force ;  in  which 
event  it  is  only  necessary  to  admit  the  air  between  the  two ;  and 
this  may  generally  be  readily  effected  by  placing  the  finger  against 
the  jaw  on  one  side  and  above  the  wax,  pressing  firmly  toward  the 
center  of  the  arch  and  upward,  forcing  the  muscles  and  mucous 
membrane  somewhat  from  the  edge  of  the  cup,  and  at  the  same 
time  depressing  the  latter  on  the  same  side.  A  small  portion 
of  air  being  admitted,  it  will  soon  diffuse  itself  between  the 
adhering  surfaces  and  allow  the  wax  to  be  readily  detached. 

To  harden  the  wax,  so  as  to  prevent  it  from  dragging  at  the 
points  where  the  ridge  overhangs,  or  to  prevent  any  change  in  its 
shape  on  the  application  of  suffi- 
cient force  to  detach  it  from  the 
mouth,  inject  under  the  lip  and 
upon  the  cup  a  stream  of  cold 
water,  sufficient  to  chill  the  wax. 

The  writer  would  repeat,  in  this 
connection,  his  conviction  that  it  is 
impracticable,  in  most  cases,  to  ob- 
tain a  faultless  impression  of  the 
mouth  in  wax.  There  are  points, 
not  readily  accessible  to  the  fingers, 
where  the  wax  departs  from  the  ex- 
ternal and  posterior  borders  of  the 
jaw,  and  is  not,  therefore,  susceptible  of  easy  correction ;  besides, 
when  reached  and  the  remedy  applied,  there  is  no  certain  assur- 
ance that  in  pressing  the  wax  in  at  one  point  we  are  not  displacing 
it  at  another.  The  same  uncertainty,  to  a  less  degree,  in  regard  to 
results  also  attaches  to  the  use  of  the  modeling  composition.  For 
this  reason,  we  almost  invariably  use  plaster,  and  we  have  suffi- 
cient reason  to  believe  that  the  results  are  more  uniformly  suc- 
cessful. 

Manner  of  Obtaining  an  Impression  of  the  Lower  Jaw  in  Wax, 
for  Entire  Dentures. — The  method  pursued  in  securing  an  im- 
pression of  the  lower  jaw;  in  wax  for  an  entire  denture  differs  in 
no  essential  respect  from  that  described  when  taking  an  impres- 
sion for  lower  partial  pieces,  the  form  of  cup  being  represented  in 
Fig.  52.     When  the  parts  are  imbedded  in  the  wax,  the  latter 


I38  MECHANICAL   DENTISTRY. 

should  be  pressed  in  around  the  inner  border  of  the  holder,  but 
more  especially  near  the  posterior  part  of  the  ridge  on  each  side 
where  the  latter  overhang  and  approximate  each  other,  forming 
corresponding  excavations  underneath.  After  adjusting  the  wax 
to  the  ridge  along  the  border  of  the  cup,  the  latter  should  again 
be  pressed  directly  down  upon  the  jaw  before  removing  it,  to 
correct  any  partial  deformity  that  may  have  occurred  during  the 
previous  manipulations. 

Modeling  composition,  of  late  years,  has  largely  superseded 
the  use  of  wax  for  impressions.  It  is  compounded  of  gum 
dammar,  stearin,  French  chalk,  carmin,  for  coloring,  and  some 
perfume.  The  consistence  of  the  mass  depends  upon  the  relative 
quantity  of  stearin  and  chalk  introduced,  the  grades  as  manufac- 
tured being  designated  as  soft,  medium,  and  hard. 

This  material  takes  a  sharper  impression  of  the  parts  than  wax, 
and  its  elastic  property  makes  it  more  suitable  where  there  are 
overhanging  ridges,  irregularly  arranged  and  bell-crowned  teeth, 
and  dovetailed  interdental  spaces.  It  is  prepared  for  use  by  soft- 
ening it  either  with  dry  heat,  or  by  immersing  it  in  hot  water. 
When  sufficiently  plastic,  it  is  introduced  into  a  cup  slightly 
heated  to  render  the  material  somewhat  adhesive,  and  then  placed 
in  the  mouth  as  has  been  directed  for  wax  impressions. 

Before  removing  it  from  the  mouth,  it  should  be  cooled  some- 
what in  order  to  preserve  its  form  unchanged.  Excessive  hard- 
ness, however,  should  be  avoided  where  portions  are  pressed  into 
unusual  undercut  spaces,  as  the  force  necessary  to  detach  it  in 
such  cases  may  produce  deformity  of  the  body  of  the  impression, 
more  or  less  remote  from  the  teeth  and  spaces  mentioned.  When 
removed  it  should  be  immediately  dipped  in  cold  water.  The 
general  manipulation  of  the  compound  in  the  mouth,  both  in  full 
and  partial  cases,  is  the  same  as  that  described  when  wax  is  used, 
and  the  same  care  should  be  observed  when  removing  the  im- 
pression from  the  mouth. 

Moldine. — This  plastic  compound,  originated  by  Dr.  George 
W.  Melotte,  and  used  by  him  chiefly  in  connection  with  crown- 
and  bridge-work,  is  composed  of  potter's  clay  mixed  with  glycerin 
to  the  consistency  of  stiff  putty.  With  the  observance  of  certain 
precautions  in  the  use  of  this  material,  the  operator  is  enabled 
very  quickly  to  secure  a  metallic  die  and  counter-die  immediately 
from  the  impression. 


IMPRESSIONS    OF    THE    MOUTH. 


139 


The  following,  in  substance,  is  Dr.  Melotte's  method  of  using 
it  and  of  obtaining  the  die  and  counter-die.  Make  the  tooth  or 
teeth  perfectly  dry,  and,  filling  the  cup  (Fig.  53)  nearly  full  with 
moldine,  coat  it  with  soapstone  powder,  and  take  the  impression 
in  the  usual  manner.  Carefully  remove  the  cup ;  trim  off  any 
overhanging  material,  and  place  the  rubber  ring  (Fig.  54)  over 
the  cup  to  about  one-half  the  depth  of  the  ring.  Melt  the  fusible 
metal  and  pour  it  as  cool  as  it  will  run  from  the  iron  ladle.  As 
soon  as  the  metal  is  hard,  remove  it  with  the  ring,  taking  care  not 
to  impair  the  impression,  which  can  be  used  again  if  the  die  is 
found  imperfect  or  is  injured  in  use.  Place  the  die  and  ring  in 
cold  water,  to  remain  until  quite  cooled.  While  the  die  is  wet  and 
held  over  a  basin  of  water,  pour  into  the  ring  fusible  metal  which 
has  been  stirred  until  it  begins  to  granulate,  and  quickly  immerse 

Fig.  53.  Fig.  54. 


all  in  the  water.  The  die  and  counter-die  should  separate  readily 
by  tapping  them  with  a  hammer,  but  if  they  stick,  others  can  be 
quickly  made  from  the  same  impression,  by  the  same  method, 
using  more  care. 

Plaster-of-Paris. — Plaster-of-Paris,  or,  technically,  calcium  sul- 
phate, has  been  long  employed  in  taking  impressions  of  the  mouth 
for  entire  dentures,  and  of  late  years  it  has  almost  entirely  super- 
seded the  use  of  all  other  materials,  on  account  of  its  capability  of 
receiving  a  practically  faultless  imprint  of  the  parts  on  which  the 
substitute  rests.  The  same  quality  of  exactness  recommends  it 
also  in  partial  cases  where  conditions  exist  that  render  an  accurate 
impression  of  the  parts  with  other  materials  impossible.  ' 

Derivation. — Plaster  is  derived  from  gypsum  by  a  process  of 
calcination.  The  latter,  or  gypsum,  is  a  common  mineral,  fre- 
quently crystallized,  oftener  amorphous,  and  oftentimes  forming 
rock  masses.     Its  transparent  variety,  called  selenite,  sometimes 


I_(.0  MECHANICAL   DENTISTRY. 

occurs  in  large  plates,  which  have  been  used  for  windows.  It  also 
frequently  occurs  in  aggregated  needle-like  crystals,  and  is  then 
called  fibrous  gypsum.  In  its  amorphous  condition,  when  com- 
pact and  translucent,  it  is  named  alabaster.  More  commonly  it  is 
white,  opaque,  and  soft,  and  is  then  called  snowy  gypsum.  The 
most  important  deposits  known  are  those  of  the  Paris  basin  at 
Montmartre,  from  which  it  has  taken  the  common  name  of  plas- 
ter-of-Paris. 

Manner  of  Preparing. — In  the  preparation  of  plaster,  as  used 
in  the  arts,  the  gypsum  rock  is  ground  between  burstones  until  it 
is  reduced  to  a  fine  powder,  when  it  is  calcined  by  being  heated 
in  kettles  or  stills,  the  combining  water  being  thus  driven  off. 
If,  in  this  condition,  it  is  again  mixed  with  water,  the  latter  re- 
combines  with  it,  the  mass  becoming  first  plastic,  and  then  solid. 
Hence,  it  is  admirably  adapted  to  a  great  variety  of  modeling 
processes.  In  its  ordinary  calcined  form,  plaster  absorbs  mois- 
ture from  the  atmosphere,  and  should,  therefore,  be  carefully  pro- 
tected from  dampness.  Should  the  latter  occur,  however,  the  un- 
combined  moisture  may  be  driven  off  by  exposing  the  plaster  to 
a  moderate  heat  in  a  shallow  pan  or  other  suitable  vessel. 

In  the  process  of  hardening,  after  having  been  made  plastic  by 
the  addition  of  water,  more  or  less  expansion  of  the  mass,  both 
during  and  for  a  time  after  solidification  takes  place,  varying 
with  the  kind  of  plaster  used  and  the  various  methods  employed 
in  preparing  it  for  molding  purposes. 

To  hasten  the  setting  of  plaster  use  warm  water  for  mixing, 
or  add  about  ten  grains  of  common  salt  (sodium  chlorid)  to  the 
water  before  introducing  the  plaster,  when  about  to  take  an  im- 
pression. The  salt  also  makes  the  plaster  more  brittle,  which  is 
desirable  in  impressions.  It  is  better  to  add  the  salt  before  the 
plaster,  as  it  gives  it  a  better  opportunity  to  become  uniformly 
diffused.  Other  agents,  such  as  chlorate  of  potash,  potassium 
sulphate,  and  alum,  have  been  and  are  used  to  hasten  the  setting 
of  plaster;  but  salt  is  the  least  objectionable  and  answers  every 
purpose. 

Manner  of  Obtaining  an  Impression  of  the  Mouth  in  Plaster, 
for  Partial  Upper  and  Lower  Dentures. — In  partial  cases, 
whether  above  or  below,  there  are,  almost  universally,  conditions 
associated    with   the   presence   of   the    remaining   natural    teeth, 


IMPRESSIONS    OF   THE    MOUTH.  I4I 

which,  until  more  recently,  have  been  thought  to  contraindicate 
the  use  of  plaster  as  an  impression  material,  but  experience  has 
demonstrated  that,  with  the  adoption  of  certain  available  means 
and  careful  and  skilful  manipulation,  there  are  few  if  any  cases  in 
which  this  material  may  not  be  successfully  employed.  Its  supe- 
rior capabilities  of  receiving  a  faultless  imprint  of  the  mucous 
surfaces  recommend  it  for  this  purpose  in  all  suitable  cases. 

The  conditions  mentioned  above  relate  to  those  cases  where 
the  cervical  portions  of  the  crowns  are  relatively  small ;  or  where 
the  teeth  are  irregularly  arranged  in  the  circle,  having  either  an 
anterior,  posterior,  or  lateral  obliquity ;  or  where  there  are  marked 
depressions  or  fossae  on  the  external  border  of  the  alveolar  ridge ; 
and  especially  where  there  are  well-defined  dovetailed  or  wedge- 
shaped  interdental  spaces.  These  conditions  prevail  in  different 
degrees  in  individual  cases,  and  the  instances  are  exceedingly  rare 
where  some  or  all  of  them  are  not  present.  As  plaster  prepared 
for  impressions,  in  the  act  of  setting  or  hardening,  becomes  rigid 
and  unyielding,  and  therefore  practically  incapable  of  any  change 
of  form  by  distortion  or  dragging  of  any  portion  of  it  on  traction, 
the  difficulty,  not  to  say  impossibility,  of  detaching  it  by  the  ordi- 
nary means,  where  these  conditions  prevail,  will  be  apparent.  In 
cases  of  very  slight  deviation  from  the  normal  position  of  the 
teeth,  sufficient  force,  judiciously  applied,  will  disengage  the  im- 
pression, provided  the  plaster  is  not  allowed  to  set  hard. 

If  the  mal-arrangement  of  the  teeth  is  considerable,  or  very 
pronounced,  the  separation  of  the  plaster  impression  must  be 
accomplished  in  some  other  way  than  by  simple  traction.  Prof. 
Charles  J.  Essig  recommends  the  following  method  of  proce- 
dure: 

"  An  impression-cup  should  first  be  selected  of  the  proper  size 
and  shape — those  with  the  flat  floor  (Fig.  47)  are  best  for  partial 
cases ;  the  plaster  should  be  mixed  quite  thin,  adding  chlorid  of 
soda  to  facilitate  setting.  Plaster  mixed  in  this  manner  does  not 
become  so  hard  and  unyielding  as  that  mixed  merely  to  satura- 
tion. Now  oil  the  cup  so  that  it  will  readily  separate  from  the 
impression  when  hard ;  fill  the  cup  as  soon  as  the  plaster  thickens 
sufficiently,  then,  with  a  small  spatula,  place  a  layer  of  the  soft 
plaster  in  upon  the  palatine  surface,  otherwise,  by  enclosing  the 
air  in  the  deep  portion  of  the  arch,  the  accuracy  of  the  impression 


142  MECHANICAL    DENTISTRY. 

may  be  impaired.  After  this  precaution,  the  cup  is  placed  in  the 
mouth,  and  gently  pressed  up  until  its  floor  comes  in  contact  with 
the  teeth.  When  the  plaster  is  sufficiently  hardened,  remove  the 
cup,  which,  from  its  having  been  oiled,  is  done  without  difficulty ; 
with  the  thumb  and  index  finger  break  off  the  outside  walls ;  the 
portion  covering  the  palatine  surface  is  then  removed  by  the  use 
of  a  blunt  steel  spatula,  curved  at  the  end  in  the  form  of  a  hook. 
The  pieces  are  then  placed  back  into  the  cup,  where  they  will  be 
found  to  articulate  with  perfect  accuracy. 

"  Should  the  first  attempt  be  rendered  futile,  by  the  tendency  to 
nausea  or  troublesome  gagging  on  the  part  of  the  patient,  camphor 
water,  as  recommended  by  Dr.  Louis  Jack,  may  be  used  as  a  gar- 
gle, which  will,  in  nearly  every  case,  prove  an  effectual  remedy." 

This  device  is  effectual  to  the  extent  described  by  Prof.  Essigr 
but  it  affords  only  a  partial  remedy  for  difficulties  which  present 
themselves  in  many  of  these  cases.  The  most  formidable  ob- 
stacle to  the  removal  of  a  plaster  impression  will  be  found  gen- 
erally in  that  portion  of  it  embraced  in  wedge-shaped  interdental 
spaces,  and  undercuts  formed  by  truncated,  cone-shaped  crowns, 
and  malpositions  of  the  teeth ;  and  when  the  outside  walls  of  the 
impression  alone  are  broken  off,  and  remaining  portions  are  im- 
bedded in  these  undercuts,  it  will  rarely  be  possible  to  remove 
the  portion  covering  the  palatal  surface  without  further  fracture 
and  removal  by  sections. 

The  writer  is  indebted  to  Prof.  Wilbur  F.  Litch  for  the  follow- 
ing description  and  illustration  (Fig.  55)  of  a  method  of  securing 
plaster  impressions  for  partial  cases : 

"  A  wax  impression-tray  is  made,  and  either  scored  or  perfor- 
ated, to  afford  anchorage  for  the  plaster.  This  extends  only  mid- 
way of  teeth  or  interspace.  After  the  plaster  has  hardened,  the 
outer  edge  is  trimmed,  notched,  and  oiled  in  the  mouth,  and  sec- 
tions D  D  of  the  diagram  made  by  carrying  plaster  into  position 
by  means  of  a  spatula,  the  outer  section  being  made  in  two  pieces, 
joined  at  about  the  median  line.  The  three  pieces  are  removed 
separately  and  joined  by  means  of  the  notches  made  in  the  pala- 
tine section  C,  into  which  notches  the  plaster  of  sections  D  D 
will  fit.  After  the  three  sections  are  cemented  together,  they  may 
be  imbedded  in  plaster,  to  more  securely  hold  them  together 
while  the  model  is  being  poured." 


IMPRESSIONS    OF    THE    MOUTH. 


143 


Another  method  of  securing  plaster  impressions  in  sections  is 
the  following,  suggested  by  Dr.  A.  G.  Bennett: 

"  A  wax  cut-off  is  placed  in  the  floor  of  the  impression-tray  in 
such  manner  that  it  will  touch  the  crowns  of  the  molars  and  the 
cutting  edges  of  the  incisors  about  midway  between  their  buccal 

Fig.  55. 


A  A.  Teeth  or  interspace.  B.  Wax  impression-tray.  C.  Plaster  impression  of 
palatine  vault  and  palatal  half  of  teeth  or  interspace.  D  D.  Buccal  or  labial 
half  of  teeth  or  interspace.     E.    Palatal  vault. 

or  labial  and  palatine  walls,  as  shown  in  Fig.  56,  letters  D  D. 
After  the  wax  cut-offs  have  been  firmly  attached  to  the  tray  by 
heat,  the  tray  is  oiled,  filled  with  plaster,  and  placed  in  position  in 
the  mouth.  After  the  plaster  has  hardened,  the  tray  is  with- 
drawn, the  plaster  remaining  in  the  mouth,  when  the  outer  sec- 


A  A.  Molar  teeth.  B.  Palatine  vault.  C  C  C.  Impression-tray.  D  D.  Wax 
cut-offs.  E  E.  Labial  sections  of  plaster  impressions.  F.  Palatal  section  of 
impression. 

tions,  E  E,  are  readily  broken  off,  and  the  plaster  section,  F,  with- 
drawn. The  several  pieces  are  then  replaced  in  their  proper  posi- 
tion in  the  tray." 

Another  method  of  procedure  in  the  class  of  cases  under  con- 
sideration is  that  described  by  the  late  Dr.  F.  M.  Dixon,  of  Phila- 
delphia, which  seems  to  provide  more  perfectly  for  the  removal  Of 
the  palatal  portion  of  the  impression  in  cases  characterized  by  un- 


144 


MECHANICAL   DENTISTRY. 


usual  inward  inclination  of  the  teeth.  The  process  described  re- 
lates to  partial  upper  cases  : 

"  First  take  an  impression  of  the  whole  upper  jaw  in  wax,  and 
harden  by  applying  ice-water.  Divide  this  impression,  with  a 
slightly  heated  knife-blade,  into  the  number  of  sections  desired 
for  the  plaster  impression.  From  the  inner  surfaces  of  these  sec- 
tions, a  sufficient  quantity  of  the  wax  is  cut  away  to  make  room 
for  the  required  amount  of  plaster.  Hard-setting  plaster  is  then 
poured  into  one  of  the  palatal  sections,  and  the  latter  placed  in 
its  proper  position  in  the  mouth,  securing  an  impression  of  the 
palatal  surfaces  of  the  teeth  of  that  side,  and  about  one-third  of 
the  palate  of  the  same  side.  When  the  plaster  has  hardened  suf- 
ficiently, the  section  is  removed  and  laid  to  one  side  while  an 
impression  of  the  opposite  side  is  secured  in  the  same  manner. 

"The  patient  may  now  be  dismissed  with  an  appointment  for 
another  sitting.  In  the  interim,  these  sections  are  carefully 
trimmed  in  such  a  manner  that  the  lower  or  lingual  surface  shall 
present  a  bevel  from  margins  near  the  mesial  line  of  the  palate  to 
the  grinding  surfaces  of  the  teeth,  that  the  next  section  may  be 
readily  removed  after  the  hardening  in  the  mouth.  When  the 
patient  returns,  the  prepared  lateral  sections,  oiled  on  their  under 
surfaces,  are  placed  in  the  mouth,  and  an  impression  of  the  cen- 
tral portion  of  the  palate  and  palatal  surfaces  of  the  incisors  is 
secured  as  before.  The  impressions  of  the  buccal  surfaces,  when 
needed,  are  taken  in  like  manner,  with  the  other  sections  in  situ." 

Manner  of  Obtaining  an  Impression  of  the  Mouth  in  Plaster 
for  Entire  Upper  Dentures. — The  form  of  cup  used  in  securing 
an  impression  of  the  upper  jaw  for  entire  sets  of  teeth  differs  in 
no  essential  respect  from  that  recommended  when  wax  is  used  for 
similar  purposes  (Fig.  51).  If  the  external  border  of  the  alveolar 
ridge  is  very  deep,  or  there  is  considerable  space  intervening 
between  the  heel  of  the  cup  and  the  floor  of  the  palate,  a  rim  of 
wax  should  be  placed  across  the  posterior  border  of  the  cup,  to 
carry  the  plaster  well  up  at  this  point,  so  as  to  secure  an  accurate 
impression,  and  more  effectually  to  confine  the  plaster  within  the 
cup  and  prevent  its  escape  into  the  back  part  of  the  mouth  before 
it  has  fairly  reached  the  palatal  vault.  If  the  latter  is  extremely 
deep,  with  a  marked  excavation  in  its  central  and  anterior  por- 
tion, or  if  it  presents,  somewhat,  the  form  of  a  deep  fissure,  the 


IMPRESSIONS    OF    THE    MOUTH.  1 45 

plaster  may  fail  to  be  carried  perfectly  against  the  floor  of  the 
palate,  or  the  air,  becoming  confined  within  the  central  portion  of 
the  arch,  when  the  plaster  is  pressed  up,  may  displace  the  latter 
and  form  corresponding  chambers  in  the  impression.  If  these 
imperfections  are  but  slight,  they  may  be  subsequently  remedied 
either  by  filling  up  the  cavity  or  cavities  in  the  impression,  or  by 
trimming  away  at  these  points  from  the  model.  The  better  plan, 
however,  where  these  conditions  of  the  vault  prevail,  is  to  take 
up  a  small  portion  of  plaster  on  the  end  of  a  spatula  and  apply  it 
to  the  deeper  portions  of  the  arch  just  before  introducing  the  cup. 
In  preparing  plaster  for  use  in  these  cases,  it  should  be  so  treated 
as  to  insure  quick  setting  when  applied  to  the  mouth.  This  is 
generally  accomplished  either  by  adding  to  a  very  thin  mixture  of 
plaster  and  water  a  small  quantity  of  sodium  chlorid  or  common 
salt  and  stirring  until  it  begins  to  thicken.  It  then  adapts  itself 
readily  to  the  parts,  hardens  quickly,  and  is  not  liable,  with  ordi- 
nary care,  to  incommode  the  patient  by  running  back  too  far  upon 
the  soft  palate  or  into  the  fauces.  So  quickly,  indeed,  does  it  con- 
dense, that  unless  expeditiously  introduced  into  the  mouth,  it  will 
begin  to  "  set "  before  the  parts  are  fairly  imbedded.  When  pre- 
paring it  for  use,  therefore,  the  plaster  should  be  mixed  at  the 
chair  with  the  cup  conveniently  at  hand,  while  the  patient  should 
be  in  proper  position,  and  in  immediate  readiness  for  the  opera- 
tion. 

In  view  of  the  liability  of  the  plaster  to  run  back  into  the  fauces 
when  the  cup  is  pressed  to  its  place  in  the  mouth,  producing  nau- 
sea and  involuntary  retching,  and  which  is  very  liable  to  occur 
whenever  the  mixture  is  too  thin  or  is  improperly  manipulated, 
it  is  recommended  to  instruct  the  patient  to  avoid  swallowing 
while  the  plaster  is  in  the  mouth,  and  to  breathe  entirely  through 
the  nostrils,  which  act  keeps  the  mouth  and  throat  quiet,  and 
hence  less  liable  to  irritation  from  the  impression  material,  and 
the  accumulation  of  saliva  in  the  mouth. 

Position  of  Patient,  etc. — The  patient  being  seated  as  nearly 
upright  in  the  chair  as  possible,  with  the  head  inclined  slightly 
forward,  the  cup  is  filled  with  the  plaster  mixture  and  introduced 
quickly  into  the  mouth,  when  it  is  pressed  up  slowly  and  gently 
(the  rear  or  heel  of  the  cup  first,  which  causes  most  of  the  sur- 
plus plaster  to  be  forced  forward),  until  the  parts  are  completely 


I46  MECHANICAL  DENTISTRY. 

encased  and  portions  of  plaster  are  seen  to  protrude  from  all 
parts  of  the  margins  of  the  cup,  otherwise  the  impression  is  liable 
to  be  imperfect,  either  on  its  outer  borders  or  on  its  posterior 
palatal  face.  Immediately  after  introducing  and  pressing  up  the 
cup,  the  lip  in  front  should  be  extended  and  drawn  down  over  the 
cup,  when  gentle  pressure,  as  the  plaster  is  hardening,  may  be 
made  upon  the  lip  and  cheeks,  to  force  the  plaster  more  perfectly 
into  close  contact  with  the  outer  surface  of  the  alveolar  ridge. 

It  is  essential  to  perfect  success  in  this  operation  that  the  cup, 
after  the  parts  are  once  imbedded,  should  be  held  perfectly  sta- 
tionary until  the  plaster  becomes  fixed,  as  the  slightest  movement 
when  the  plaster  is  in  the  act  of  consolidating  will  derange  the 
impression  and  render  it  faulty.  Again,  if  after  the  parts  are  im- 
bedded the  operator  discovers  that  they  are  not  sufficiently  en- 
cased, and  the  plaster  has  partially  set,  no  further  effort  should  be 
made  to  press  the  plaster  up  upon  the  parts,  but  the  cup  should  be 
withdrawn  and  the  operation  repeated  with  fresh  plaster. 

If  the  operation  has  been  successfully  conducted,  the  plaster 
will  adhere  to  the  mouth,  in  most  instances,  with  great  tenacity, 
and  it  will  be  necessary  to  observe  some  caution  in  removing  it, 
for,  if  forcibly  detached,  injury  may  be  inflicted  upon  the  soft 
parts  by  tearing  away  portions  of  mucous  membrane ;  or  the  im- 
pression may  be  badly  fractured  or  otherwise  impaired.  In  addi- 
tion to  the  means  already  alluded  to  in  connection  with  the 
method  of  separating  wax  impressions  from  the  mouth,  resort  is 
sometimes  had  to  the  following  expedient :  The  central  portion 
of  the  cup  being  pierced  with  two  or  three  small  holes,  a  blunt- 
pointed  probe  is  passed  at  these  points  through  the  plaster,  before 
the  latter  has  hardened  perfectly,  to  the  roof  of  the  mouth.  Into 
these  passages  the  external  air  passes  and  diffuses  itself  between 
the  surface  of  the  plaster  and  the  palate,  when  the  impression  may 
be  readily  detached.  The  writer,  however,  has  succeeded  best 
in  detaching  impressions  in  such  cases  by  upward  and  interrupted 
traction  upon  the  handle  of  the  cup,  which,  by  depressing  the 
latter  posteriorly,  more  readily  permits  the  introduction  of  air 
than  by  either  of  the  methods  commonly  employed. 

Manner  of  Obtaining  an  Impression  of  the  Mouth  in  Plaster, 
for  Entire  Lower  Dentures. — The  general  form  of  cup  used  for 
the  above  purpose  is  shown  in  Fig.  52.     This  being  filled  with  the 


IMPRESSIONS    OF    THE    MOUTH. 


147 


plaster  mixture,  prepared  as  described  in  connection  with  full 
upper  pieces,  is  inverted  and  quickly  introduced  into  the  mouth 
and  pressed  down  upon  the  ridge  until  the  latter  is  completely 
imbedded,  being  careful  at  the  same  time  to  draw  the  lower  lip 
away  from  the  cup,  and  the  cheeks  outward,  in  order  to  prevent 
any  loose  tissues  from  folding  in  upon  the  outer  borders  of  the 
ridge  as  the  cup  is  pressed  to  place,  thus  seriously  marring  the 
impression. 

It  is  thought  by  many  operators  that  better  results  can  be 
secured  by  first  taking  the  impression  in  wax,  enlarging  the  im- 
pression thus  secured  with  suitable  instruments,  and  using  this 
as  a  tray  for  plaster. 


CHAPTER  XIV. 

PLASTER  MODELS. 

After  an  impression  of  the  mouth  has  been  secured  in  either  of 
the  ways  mentioned  in  the  preceding  chapter,  the  next  step  in  the 
process  of  constructing  an  artificial  denture  is  to  procure  from 
the  impression  a  representation  of  the  parts  in  plaster.  The  copy 
thus  secured  is  called  a  model,  or  cast,  and  if  correctly  obtained 
is  a  true  counterpart,  or  facsimile,  of  all  parts  of  the  mouth  rep- 
resented in  the  impression. 

Manner  of  Obtaining  a  Plaster  Model  from  an  Impression  in 
Wax  or  Modeling  Compound,  for  Partial  Dentures. — The  im- 
pression should  be  first  trimmed  by  cutting  away  superfluous 
portions  that  overhang  the  borders  of  the  cup,  care' being  taken 
not  to  mar  any  essential  part  of  the  impression.  The  surface 
imprinted  should  then  be  uniformly  and  thinly  coated  with  soapy 
water  or  oil,  applied  with  a  camel's-hair  brush.  This  should  not 
be  of  too  thick  a  consistency,  nor  applied  in  too  large  quantities, 
as  it  will  collect  in  the  more  depending  portions  of  the  impres- 
sion, and,  failing  to  be  displaced  by  the  plaster,  leave  the  model 
imperfect  at  these  points,  especially  at  the  coronal  extremities  of 
the  plaster  teeth.  The  cup  is  now  surrounded  by  some  substance 
that  will  confine  the  plaster  and  give  proper  form  to  the  body  of 
the  model.  For  this  purpose  any  material  that  is  easily  shaped 
may  be  used,  as  a  thin  sheet  of  lead  or  wax,  paper,  strips  of  oil- 
or  wax-cloth,  etc. 

Before  pouring  the  plaster,  if  it  is  desired  to  strengthen  any  of 
the  plaster  teeth — as  those  adjoining  the  vacuities  in  the  jaw,  or 
such  as  are  to  be  used  in  adjusting  clasps — and  thus  secure  them 
against  accident  in  handling,  adequate  support  may  be  imparted 
to  them  by  placing  short  pieces  of  stiff  wire  vertically  in  the  de- 
pressions made  in  the  impression  by  the  teeth,  supporting  them 
in  an  upright  position  by  imbedding  one  end  in  the  wax  or  other 
material  in  the  center  of  the  bottom  of  each  cavity. 

When  the  cup  is  properly  inclosed,  a  batter  of  plaster,  of  some- 

148 


PLASTER    MODELS. 


149 


what  thinner  consistency  than  that  used  for  impressions,  is 
poured  in  upon  the  surface  of  the  wax  in  sufficient  quantity  to 
give  to  the  body  of  the  model  a  depth  of  from  one  to  three  inches, 
according  to  the  particular  requirements  of  the  case.  The  plas- 
ter should  not  be  poured  directly  or  hastily  into  the  cavities 
formed  by  the  teeth,  but  upon  points  contiguous  to  them,  and 
from  which  it  should  be  allowed  to  run  slowly  into  the  depres- 
sions, by  tapping  the  bottom  of  the  cup  gently  upon  the  table, 
thus  expelling  the  contained  oil  or  air,  and  filling  them  perfectly. 
When  the  plaster  has  become  sufficiently  hard,  any  portions  over- 
lapping the  borders  of  the  impression,  and  not  essential  to  the 
form  of  the  model,  should  be  cut  away  and  the  two  separated  by 
immersion  in  warm'  water  until  the  warmth  imparted  to  the  model 
renders  the  impression  sufficiently  soft  to  allow  the  former  to  be 
removed  without  fracturing  the  plaster  teeth. 

The  general  form  of  the  body  of  a  model  is  shown  in  Fig. 
58.  Where  a  swaged  base  is  required,  the  walls,  as  will  be  seen, 
are  made  as  nearly  vertical  or  parallel  as  will  admit  of  the  model 
being  readily  detached  from  the  sand  in  the  process  of  molding; 
for  if  made  too  flaring  or  divergent,  the  metallic  die  obtained 
from  it  will  be  more  liable  to  crack  or  spread  apart  under  the 
repeated  strokes  of  a  heavy  hammer,  or  to  rock  under  one-sided 
blows. 

During  the  process  of  stamping  or  forcing  a  metallic  base  into 
adaptation  to  the  die — which  is  a  metallic  counterpart  of  the 
model — the  plate,  when  cut  to  the  exact  pattern  of  the  parts  to  be 
covered  by  it,  is  frequently  forced  or  dragged  back  toward  the 
heel  of  the  die,  and  is  thus  drawn  from  the  teeth  at  the  sides  and 
in  front.  This  displacement  of  the  plate  may  be  prevented  by 
cutting  away  all  of  the  plaster  teeth  from  the  model,  leaving,  how- 
ever, enough  of  them  remaining  where  they  unite  with  the  body 
of  the  model  to  form  a  shoulder  to  each  tooth,  as  in  Fig.  57.  In 
this  case  the  plate  should  be  sufficiently  ample  in  its  dimensions 
partially  to  overlap  the  border,  when,  as  it  is  forced  into  adapta- 
tion, distinct  indentations  will  be  made  in  it,  corresponding  ex- 
actly with  the  palatal  curvatures  of  the  teeth ;  the  portions  of  the 
plate  covering  the  cut  ends  of  the  teeth  are  then  cut  away  with 
plate  forceps  or  other  instruments.  If,  however,  the  plate  is  of 
the  exact  size  required  before  stamping,  one  or  two  plaster  teeth 


150 


MECHANICAL  DENTISTRY. 


upon  each  side  of  the  model  may  be  allowed  to  remain,  against 

the  anterior  face  of  which  the  plate  is  made  to  rest,  holding  it 

stationary. 

Fig.  57. 


Manner  of  Obtaining  a  Plaster  Model  from  an  Impression  in 
Wax  or  Modeling  Compound,  for  Entire  Dentures. — The  same 
general  method  is  pursued  in  obtaining  a  plaster  model  from  an 

Fig.  58. 


Fig.  59. 


impression  of  either  the  upper  or  lower  jaw  for  entire  dentures 
with  the  substances  mentioned,  as  that  employed  in  partial  cases. 
The  general  form  of  these  pieces  is  represented  in  Figs.  58  and  59. 


PLASTER    MODELS.  I5I 

If  it  is  desired  to  swage  a  rim  to  the  plate,  forming  a  groove  or 
socket  into  which  the  plate  extremities  of  the  teeth  are  received, 
the  model  should  be  formed  in  the  manner  represented  in  the  an- 
nexed cuts ;  in  which  it  will  be  seen  that  an  abrupt  shoulder  is 
formed  on  the  external  border  of  the  model  of  the  upper  jaw  (Fig. 
58),  but  which  on  the  lower  (Fig.  59)  is  extended  round  the  inner 
border  also,  as  it  is  desirable,  in  the  latter  case,  to  give  a  rounded 
edge  to  the  lingual  border  of  the  plate,  and  which  is  accomplished 
in  part  by  swaging  in  the  first  instance  and  afterward  by  turning 
the  edge  down  upon  the  plate  with  pliers  or  by  other  means. 
The  model  is  prepared  by  adjusting  a  strip  of  softened  wax 
around  the  border,  and  cutting  away  from  its  upper  surface  in 
such  a  way  as  to  form  a  groove,  the  bottom  of  which  shall  be  on 
a  line  with  the  extreme  edge  of  the  base  or  plate,  which  should 
be  indicated  upon  the  model  with  a  pencil  mark  before  applying 
the  roll  of  wax. 

Rimmed  plates,  however,  are  only  required  when  single  gum 
teeth,  or  sectional,  or  entire  blocks  are  employed,  or  when  plate 
teeth  are  mounted  on  a  platinum  base  with  continuous  gum. 

Forming  the  Air-chamber. — Whenever  an  air-chamber  is  to 
be  stamped  in  the  base,  the  model  should  be  prepared  for  the  pur- 
pose before  casting  the  metallic  swages.  The  general  form  and 
position  of  the  central  cavity  or  chamber  in  the  arch  is  represented 
in  Fig.  58.  The  model  may  be  prepared  in  either  of  the  following 
ways:  1.  The  form  of  the  chamber  may  be  cut  from  the  wax  or 
plaster  impression,  in  which  case  the  plaster  will  be  raised  at  a 
corresponding  point  or  points  upon  the  model,  and  will  have  ex- 
actly the  same  form  and  depth  as  the  cavity  in  the  impression.  2. 
Cover  the  palatal  face  of  the  model  with  a  sheet  of  wax  equal  in 
thickness  to  the  required  depth  of  the  chamber,  and  cut  out  from 
this,  at  the  desired  point,  the  form  of  the  cavity ;  fill  the  latter  with 
plaster,  and  when  hard  remove  the  wax  and  trim  the  raised  por- 
tion to  the  proper  form.  3.  Cut  a  pattern,  of  the  required  form 
and  depth  of  chamber,  from  sheet-wax  or  lead ;  place  it  in  proper 
position  in  the  arch,  and  press  down  with  the  fingers  or  burnisher 
until  it  conforms  to  the  contour  of  the  palate  ;  it  is  then  fixed  in 
place  either  by  confining  it  with  a  small  pin  or  tack  driven  through 
it  into  the  plaster,  or  by  interposing  softened  wax  or  other  adhe- 
sive material  between  the  pattern  and  model.     A  small  brush 


i52 


MECHANICAL  DENTISTRY. 


loaded  with  a  varnish  mixture  passed  around  the  edge  of  the  pat- 
tern will  insure  sufficient  adhesion. 

The  same  general  method  as  that  when  central  chambers  are 
formed  is  pursued  in  the  preparation  of  the  model  when  it  is  de- 
sired to  construct  lateral  cavities  in  the  plate.  The  form  and 
position  of  these  on  the  model  will  be  indicated  by  inspection  of 
the  form  of  "  lateral  cavity  "  plates  as  exhibited  in  the  chapter  on 
Entire  Dentures. 

There  are  other  modifications  in  the  form  of  cavity  plates,  some 
of  which  are  obsolete ;  that  known  as  "  Cleveland's  chamber  "  is 
still  in  limited  use,  but  does  not  require  a  model  differing  in  form 
from  the  one  described  in  connection  with  full  dentures  with 
central  chambers. 

Manner  of  Obtaining  a  Plaster  Model  from  an  Impression  in 
Plaster,  for  Partial  Dentures. — The  surface  of  the  impression  in 
plaster  should  be  first  glazed,  by  applying  to  it,  with  a  camel's- 
hair  brush,  a  uniform  coating  of  varnish,  to  prevent  adhesion  of 
the  model.  Two  kinds  of  varnish  are  in  common  use — a  trans- 
parent and  a  colored.  The  former  is  preferred,  for  the  reason 
that  it  penetrates  the  plaster  more  thoroughly,  giving  to  it  a 
greater  depth  of  surface  hardness,  while  the  latter,  if  not  suffi- 
ciently fluid,  forms  a  somewhat  superficial  incrustation,  which  is 
liable  to  peel  off  in  handling,  leaving  portions  of  the  model  unpro- 
tected. Either,  however,  if  properly  prepared  and  applied,  may 
be  employed. 

Formula  No.   I.  Formula  No.   2. 

TRANSPARENT  VARNISH.  COLORED  VARNISH. 

Gum  sandarach,    5  oz.  Gum    shellac,    5   oz. 

Alcohol,    1    quart.         Alcohol,    1   quart. 

The  sandarach  or  shellac  should  first  be  freed  from  all  impuri- 
ties by  careful  picking  and  washing;  they  are  then  added  to  the 
alcohol  and  digested  over  a  moderate  heat  until  thoroughly  dis- 
solved. Other  substances,  as  gum  elcmi,  Venice  turpentine,  etc., 
have  been  recommended  as  additional  ingredients,  but  they  are 
not  indispensable,  and  may  be  omitted  without  sensibly  impair- 
ing the  properties  of  the  varnish. 

The  varnish,  or  separating  fluid,  should  be  kept  securely  bot- 
tled, to  prevent  evaporation  of  the  alcohol,  and  keep  it  free  from 
dust  and  other  foreign  substances.     For  this  purpose  the  "  Clo- 


PLASTER    MODELS. 


153 


ver-Leaf  Holder  "  (see  Fig.  60)  is  probably  the  most  convenient, 
neat,  cleanly,  and  economical  receptacle  on  sale  for  that  purpose. 
The  body  is  of  glass  with  nickeled  mountings  and  cover.  It  con- 
tains two  compartments,  the  larger  for  the  varnish,  the  smaller 
for  the  brushes,  of  which  there  are  three,  a  large  one  attached  to 
the  lid,  and  two  smaller  ones  which  depend  from  the  partition 
between  the  compartments  by  means  of  a  little  hook.  Across  the 
main  compartment  is  a  scraper  to  remove  surplus  varnish  from 
the  brushes.  The  lid  is  held  in  place  upon  a  rubber  ring  with  a 
firm  pressure,  by  means  of  a  rubber  wheel  attached  to  a  swinging 
lever.  This  makes  the  holder  air-tight  and  prevents  evaporation 
of  the  varnish.  The  brushes  are  specially  made  for  varnish,  of 
fine  goat's  hair,  which  is  better  for  the  purpose  and  more  durable 

Fig.  60. 


than  camel's-hair.  A  little  alcohol  placed  in  the  brush  compart- 
ment keeps  the  brushes  pliable,  and  is  convenient  for  thinning  the 
varnish  when  desirable. 

After  glazing  the  surface  of  the  plaster  impression  with  var- 
nish, a  thin  and  uniform  coat  of  oil  or  soapy  water  should  be 
applied ;  it  is  then  enveloped,  and  the  model  procured  in  the  same 
manner  as  when  the  other  plastic  materials  are  used. 

The  following  method  of  preparing  the  plaster  impression  be- 
fore it  is  filled  in  for  the  model  is  recommended  by  Dr.  C.  W. 
Spalding :  "  After  the  impression  has  become  hard,  coat  the  sur- 
face with  a  lather  of  soap  and  water ;  wash  this  off  and  immerse 
the  model  in  water.  This  expels  air  and  avoids  liability  to  poros- 
ity of  the  surface  of  the  model.  Again  coat  the  surface  with  a 
strong  lather  of  soap  and  water,  and  wash  off  as  before,  when  the 
impression  is  ready  to  receive  the  plaster  for  the  model.     I  prefer 


154 


MECHANICAL  DENTISTRY. 


this  method  to  varnishing,  for  the  reason  that  the  varnish  used  is 
not  always  of  uniform  consistency." 

In  separating  the  model  from  a  plaster  impression,  for  partial 
cases,  it  will  be  necessary  to  cut  the  latter  away  in  pieces,  as  any 
attempt  to  separate  the  two  in  the  ordinary  manner  would  inevi- 
tably break  away  the  plaster  teeth  from  the  model.  The  impres- 
sion should  be  chipped  away  with  care,  to  avoid  defacing  the 
model.  To  provide  more  perfectly  against  this  accident,  it  is 
better  to  coat  the  impression  with  colored  varnish,  as  this  will 
indicate  with  greater  certainty  the  line  of  contact  or  union  be- 
tween the  two  pieces.  Dr.  Spalding  suggests  a  simple  and  effec- 
tive device  for  the  same  purpose,  which  consists  in  coloring  the 
water  used  to  mix  the  plaster  for  the  impression  with  anilin  red. 
When  separated,  the  model  should  be  trimmed  and  formed  in  the 
manner  before  described. 

Manner  of  Obtaining  a  Plaster  Model  from  an  Impression  in 
Plaster,  for  Entire  Dentures. — The  preparation  of  a  plaster  im- 
pression of  either  the  upper  or  lower  jaw,  for  full  dentures,  and 
the  method  of  procuring  a  model  therefrom,  differ  in  no  essential 
respect,  except  in  the  mode  of  separation,  from  the  manipulations 
required  when  the  impressions  have  been  taken  in  plaster  for 
partial  pieces.  A  model  can,  ordinarily,  where  there  are  no  con- 
siderable depressions  or  undercuts  on  the  external  face  of  the 
ridge,  be  readily  separated,  either  by  taking  the  model  in  the  hand 
and  tapping  the  handle  of  the  cup,  or  by  forcing  a  wedge-shaped 
instrument  between  the  impression  and  model  at  the  posterior 
border.  When,  however,  there  are  considerable  undercuts,  such 
as  usually  prevail  on  either  side  of  the  median  line  in  front,  above 
and  below,  or  the  anterior  and  middle  portions  of  the  ridge  are 
thin,  prominent,  and  overhanging,  the  application  of  sufficient 
force  to  detach  the  impression  in  a  body  will  inevitably  fracture 
such  portions  of  the  ridge  of  the  model  as  are  engaged  in  the  con- 
tracted spaces.  In  such  cases,  the  cup  being  removed  from  the 
impression,  the  latter  should  be  grooved  as  deeply  as  possible 
without  marring  the  face  of  the  model,  in  such  a  way  that,  when 
the  instrument  is  forced  in  at  suitable  points,  the  impression  will 
be  fractured  on  a  line  with  the  grooves,  and  thus  be  detached  in 
sections.  One  groove  may  be  made  continuously  along  a  line 
corresponding  with  the  summit  of  the  ridge,  and  others  extending 


PLASTER    MODELS.  I  55 

at  right  angles  with  this  to  the  outer  borders  of  the  impression. 
When  these  external  sections  are  removed  separately  by  wedging 
at  the  extreme  border  of  the  impression,  the  whole  central  portion 
will  be  easily  detached.  Extreme  thinness  and  prominence  of 
the  ridge  will  most  generally  be  found  in  connection  with  the 
lower  jaw,  and  will  require  cautious  manipulation  to  avoid  acci- 
dent to  the  model.  If  any  portion  of  the  model  should  be  de- 
faced, it  may  be  remedied  by  restoring  the  contour  with  plaster. 
After  detaching  the  model  in  the  manner  mentioned,  the  entire 
body  of  it  should  be  glazed  and  hardened  by  applying  to  it  a  thin 
and  uniform  coat  of  varnish,  if  it  is  to  be  used  in  obtaining  a 
metallic  die.  This  protective  covering  will  prevent  the  surface 
from  wearing,  render  it  more  pleasant  to  the  touch,  facilitate  its 
withdrawal  from  the  sand,  and  give  a  more  perfect  mold.  A 
model  may  be  better  prepared  for  permanent  preservation  by  im- 
mersing it  for  a  short  time  in  a  solution  of  carbonate  of  soda,  by 
which  its  surface  is  converted  into  carbonate  of  lime  and  thereby 
rendered  hard  and  durable ;  care  must  be  taken  not  to  introduce 
any  of  the  bicarbonate  of  soda  into  the  solution. 


CHAPTER  XV. 

METALLIC  DIES  AND  COUNTER-DIES. 

A  metallic  die  is  a  facsimile  or  transcript  of  the  mouth  in  metal, 
and  is  also  a  copy  or  likeness  of  the  plaster  model. 

A  metallic  counter-die  is  a  copy  of  the  impression,  and  is  a 
reversed  image  of  the  die  and  plaster  model. 

Manner  of  Obtaining  a  Metallic  Die. — Two  general  methods 
are  employed  in  procuring  a  metallic  counterpart  of  the  model : 
first,  by  molding;  second,  by  a  process  termed  "  dipping."  The 
first  only,  however, — being  the  more  practical  and  more  gener- 
ally used, — will  be  considered. 

Materials  Used  in  Molding. — For  this  purpose  the  best  mate- 
rial is  marble-dust,  though  other  substances,  as  sand,  Spanish 
whiting,  etc.,  have  been  recommended.  Marble-dust  has  the  ad- 
vantage of  being  always  ready  for  use,  or  nearly  so,  as  it  absorbs 
considerable  moisture  from  the  atmosphere  to  render  it  cohesive, 
is  cleanly,  and  gives  a  smooth  and  uniform  surface  to  the  die. 
When  sand  is  used  it  should  be  fine  and  even-grained,  the  best 
for  the  purpose  being  that  used  by  brass-founders.  It  is  pre- 
pared by  mixing  with  it  sufficient  water  to  render  its  particles 
somewhat  adherent,  so  that  when  portions  of  it  are  pressed  in  the 
hand  and  then  parted  with  the  fingers  it  will  break  away  in  well- 
defined  fragments.  Excess  of  water  should  be  avoided,  as  the 
vapor  formed  by  the  molten  metal,  when  poured  upon  it,  will 
displace  portions  of  the  latter  and  form  cavities  or  blisters  in  the 
face  of  the  die  ;  nor  should  the  sand  used  be  too  dry,  as  in  that 
case  it  will  crumble  away  in  detaching  the  model. 

Oil  lias  been  proposed  as  a  substitute  for  water,  in  which  case 
it  is  recommended  to  add  one  quart  of  the  former  to  a  peck  of 
sand.  It  is  claimed  that  the  sand  so  prepared  is  always  in  imme- 
diate readiness  for  use. 

Preparing  Model  Previous  to  Molding. — Tn  upper  cases, 
whether  partial  or  full,  a  shallow  groove  should  be  made  along 

156 


METALLIC    DIES    AND    COUNTER-DIES. 


157 


the  posterior  plate  line,  so  that  when  the  plate  is  swaged  this 
edge  will  press  firmly  against  the  roof  of  the  mouth.  The  cast 
should  also  be  carved  at  the  points  where  the  integument  of  the 
palate  is  soft  and  yielding.  In  some  cases  the  center  of  the  pala- 
tal portion  of  the  mouth  is  unusually  hard  and  unyielding ;  in  fact, 
large,  bony  prominences  are  sometimes  found ;  these  points 
should  have  a  thin  layer  of  wax  placed  over  them,  so  as  to  relieve 
the  pressure,  otherwise  the  plate  would  rock,  thus  interfering 
with  the  adhesion  and  the  wearer's  comfort.  The  form  for  the 
vacuum-chamber  should  also  be  built  up  with  wax  or  other  mate- 
rial, when  the  cast  will  be  ready  to  proceed  with  the  molding. 

Manner  of  Securing  Mold. — The  molding  material  being  prop- 
erly prepared,  the  model  is  placed  with  its  face  uppermost  on  the 
molding-board  and  surrounded  with  a  metallic  ring.  What  is 
known  as  the  Bailey  Molding-flask  is  used  by  many  operators. 
A  common  "  wagon-box,"  however,  of  which  two  or  three  sizes 
should  be  had,  will  answer  every  purpose  in  ordinary  cases.  If 
sand  is  used,  it  should  first  be  well  sifted  to  remove  the  coarser 
particles,  and  then  filled  into  the  ring,  packing  it  closely  with  the 
fingers  around  and  over  the  model  until  even  with  the  upper  edge 
of  the  box.  Some  care  must  be  observed  in  the  management  of 
the  molding  material  when  packing  it,  for,  if  made  too  compact, 
the  vapor  formed  in  pouring  hot  metal,  failing  to  pass  out  readily, 
will  be  confined  within  the  cavity  and  cause  imperfections  in  the 
face  of  the  die ;  or,  if  too  loosely  packed,  the  fluid  metal,  when 
poured  into  the  mold,  will,  to  some  extent,  permeate  the  pores  of 
the  sand  or  other  material,  and  render  the  face  of  the  die  rough 
and  imperfect. 

Manner  of  Withdrawing  the  Cast. — After  the  sand  has  been 
well  packed,  level  off  the  surface  with  a  rule,  lift  the  flask  or  ring 
with  its  contents  from  the  bench,  turn  it  over  carefully,  and  lay  it 
down  with  the  bottom  of  the  cast  up.  Now  run  the  point  of  a 
tack  or  the  small  blade  of  a  knife  into  the  center  of  the  cast  with 
a  few  gentle  taps  from  the  hammer.  Grasp  the  knife  or  head  of 
the  tack  firmly  between  the  thumb  and  fingers,  and  with  a  small 
hammer  distribute  a  few  gentle  taps  over  the  surface  of  the  cast. 
If  the  cast  cannot  then  be  withdrawn,  continue  the  process  and  at 
the  same  time  distribute  a  few  gentle  blows  over  the  edge  of  the 
molding-ring,  when  it  will  usually  be  found  that  the  cast  can  be 


158 


MECHANICAL  DENTISTRY. 


readily  lifted  out.  All  these  manipulations  must  be  very  gentle 
or  the  cast  may  be  tilted  or  rocked  in  the  sand,  and  thus  make  a 
false  impression. 

Another  method  of  removing  the  cast  from  the  sand,  usually 
given  in  the  text-books,  is  to  reinvert  the  ring  and  contents,  hold 
it  above  the  table,  and  dislodge  the  cast  by  tapping  it  gently  un- 
derneath. The  writer  would,  however,  in  nearly  all  cases  reject  a 
mold  from  which  the  cast  had  fallen  out  by  its  own  weight. 

Manner  of  Molding  where  Undercuts  are  Present. — Where  we 
have  an  overhanging  alveolar  ridge  producing  a  slight  undercut, 
the  front  of  the  cast  may  be  raised  by  first  building  an  inclined 
bed  of  the  molding  material,  and  resting  the  cast  upon  its  highest 

Fig.  6i. 


point  with  the  heel  upon  the  molding-tray  or  table,  as  is  shown  in 
Fig.  61.     It  can  then,  in  ordinary  cases,  be  readily  withdrawn. 

Molding  with  Cores. — Where  the  undercuts  are  too  great  to  be 
overcome  by  the  method  just  described,  what  is  known  as  core- 
molding  is  employed.  First  set  the  cast  on  some  smooth  surface ; 
oil  at  the  site  of  the  undercut ;  mix  plaster  and  asbestos,  or  plaster 
and  marble-dust,  equal  parts.  When  dry,  apply  the  mixture  of 
proper  consistency  to  the  front  of  the  model,  from  the  bottom  up 
to  the  edge  of  the  alveolar  line,  spreading  it  on  both  sides  so  as  en- 
tirely to  fill  up  the  depression,  making  the  lower  edge  ^2  of  an  inch 
thick,  and  sloping  off  toward  the  alveolar  ridge  (Fig.  62).  When 
this  has  hardened,  separate  it  from  the  model,  and  draw  the  top  of 


METALLIC    DIES    AND    COUNTER-DIES. 


159 


it  over  sand-paper  to  obtain  a  flat  edge,  and  let  it  dry.  Readjust 
this  front  piece  to  the  model ;  procure  a  mold  in  sand  or  other 
material,  in  the  usual  way;  place  the  extra  piece  or  core  back  in 
its  proper  position  in  the  mold,  and  proceed  to  cast  for  the  die. 
After  the  mold  is  secured,  the  core  is  removed  from  the  plaster 
model,  replaced  in  the  mold,  and  the  metal  poured. 

The  Hawes  Flask. — The  difficulty  mentioned  above  may  also 
be  overcome  by  employing  the  sectional  molding  flask  invented 
by  Dr.  G.  W.  Hawes,  the  several  parts  of  which  are  represented 
in  Figs.  63,  64,  and  65. 

Fig.  63  represents  the  lower  ring,  composed  of  three  movable 
pieces,  with  flange  extensions  that  project  in  toward  the  center. 

Fig.  62. 


When  used,  this  portion  of  the  flask  is  closed  and  the  sections 
kept  in  place  by  pins  passing  through  the  joints.  Inside  of  this 
ring  the  model  is  placed  face  upward,  the  ridge  extending  a  little 
above  the  upper  plane  of  the  ring.  Sand,  well  sifted,  is  then 
packed  in  around  the  model  on  a  level  with  the  most  projecting 
points  on  the  outside  of  the  ridge,  as  indicated  by  the  dotted  line 
in  Fig.  65.  The  surface  of  the  sand  should  be  trimmed  smoothly, 
and  should  be  cut  squarely  and  at  right  angles  with  the  ridge  to 
prevent  the  sand  from  breaking  away  when  the  model  is  with- 
drawn. Very  finely  pulverized  charcoal,  contained  in  a  loose 
muslin  bag,  is  now  sifted  over  the  exposed  surface  of  the  sand  to 
prevent  the  next  portion  contained  in  the  upper  ring  from  adher- 
ing.    The  plain  ring  (Fig.  64)  is  then  placed  over  the  one  contain- 


i6o 


MECHANICAL  DENTISTRY. 


ing  the  model,  and  is  filled  with  sand  well  packed  over  the  face  of 
the  die.  The  upper  ring  is  now  carefully  lifted  from  the  lower 
one  on  a  line  with  the  pins,  thus  separating  the  two  portions  of 
sand,  and  again  exposing  the  uncovered  face  of  the  model.  One 
of  the  pins  should  then  be  drawn  from  the  lower  ring,  the  sec- 
tions of  the  latter  carefully  unfolded,  and  the  model  withdrawn, 
when  the  ring  may  be  again  closed  and  confined  by  replacing  the 
pin.  The  upper  ring  is  then  readjusted  in  its  proper  relation  to 
the  lower  one,  the  flask  inverted,  when  the  mold,  if  the  process 
has  been  accurately  conducted,  will  be  found  perfect. 

In  obtaining  a  mold  from  the  model  of  a  lower  jaw,  but  little 
difficulty  will  ordinarily  be  experienced  in  obtaining  it  perfect  in 


Fig.  63. 


Fig.  64. 


Fig.  65. 


the  manner  first  described.  The  depressions  at  the  posterior  and 
inner  border  of  the  ridge  are  the  points  most  liable  to  drag  or  dis- 
place the  sand,  and  when  the  latter  occurs,  the  surplus  metal  in 
the  die  at  such  points  must  be  cut  away  with  suitable  instru- 
ments ;  or  the  cavities  in  the  model  may  be  so  filled  out  with  wax 
before  molding  as  to  permit  the  ready  separation  of  the  model 
without  displacing  the  sand,  in  which  case,  also,  it  will  be  neces- 
sary, afterward,  to  trim  the  redundant  metal  from  the  die. 

The  Lewis  Molding-flask. — This  form  of  flask,  introduced  by 
the  Buffalo  Dental  Manufacturing  Co.,  is  an  improvement  upon 
the  Bailey  Flask  for  making  dies  ;  the  top  part,  which  forms  the 


METALLIC   DIES    AND    COUNTER-DIES. 


161 


zinc  die,  being  entirely  new  in  shape  and  purpose.  By  the  use  of 
this  flask,  the  metal  in  the  die  is  concentrated  above  it,  so  that  it 
has  no  outside  bearing  upon  the  counter-die ;  thus  overcoming 
what  is  to  many  dentists  a  serious  objection  to  dies  produced 
with  the  ordinary  flasks  or  rings,  viz.,  the  bearing  of  the  die 
upon  the  counter,  outside  of  the  model,  preventing  the  driving  of 
the  former  into  the  latter  as  it  yields  in  swaging,  unless  the 
method  suggested  by  Dr.  Broomell  on  page  169  employed.  In 
dies  produced  by  the  Lewis  Flask,  the  bearing  of  the  die  upon 
the  counter  is  limited  to  the  model,  and  a  more  perfect  adaptation 
can  be  secured  between  it  and  the  plate.  With  this  flask  a  thin 
model  can  be  used,  at  the  same  time  all  the  advantages  of  the 
old-fashioned,  thick,  or  built-up  model  secured. 

Fig.  66 


When  this  form  of  flask  is  employed,  the  procedure  is  as  fol- 
lows :  A  thin  plaster  cast  should  be  trimmed  to  give  proper  draft 
at  the  edges ;  varnish  and  dry  thoroughly.  Before  proceeding  to 
mold,  dust  it  with  a  little  finely-powdered  charcoal,  shaking  off  all 
that  does  not  adhere.  Invert  the  top  or  winged  section  of  the 
flask,  fill  its  conical  cavity  with  sand,  leaving  it  a  little  high,  and 
press  the  back  of  the  model  firmly  upon  it,  to  secure  a  solid  foun- 
dation and  prevent  rocking.  Place  the  ring  in  position,  and  sift 
the  sand  into  it,  ramming  it  down  carefully.  Strike  off  the  surface 
of  the  sand  level  with  the  top  of  the  ring.  Reverse  the  flask,  hold- 
ing the  sections  together  securely ;  then  remove  the  winged  sec- 
tion and  draw  the  model.  Fill  the  depression  in  the  sand  with  the 
molten  metal ;  then  place  the  upper  section  of  the  flask  in  position 
— the  sand  having  previously  been  knocked  out  of  it — and  com- 
plete the  pouring  of  the  metal.     When  the  die  has  cooled,  smoke 


l62  MECHANICAL    DENTISTRY. 

its  exposed  surface,  and  replace  it  in  the  winged  part  of  the  flask ; 
knock  the  sand  out  of  the  ring,  place  it  in  position,  and  fill  with 
the  counter-die  metal. 

The  Pearsall  Molding-flask. — This  form  of  molding-flask,  as 
Mr.  Booth  Pearsall,  the  designer,  says,  is  intended  to  remove 
some  of  the  many  defects  found  in  zinc  dies  as  commonly  made 
by  dentists.  The  molding-plate  (Fig.  67)  is  circular,  and  has  on 
its  upper  surface  four  concentric  grooves  and  four  projections  or 
tabs.  The  grooves  hold  the  sand,  and  make  so  many  dikes  or 
obstructions  to  prevent  the  hot  metal  from  running  out  between 
the  molding-plate  and  the  sand.  The  grooves  also  serve  to  guide 
the  workman  in  correctly  centering  or  excentering  the  position  of 
the  model,  so  that  the  cone  or  striking  part  of  the  die  will  come 
where  most  strength  is  required — in  other  words,  where  the 
heaviest  hammering  is  to  be  done.  On  the  under  side  of  the 
molding-plate  are  four  webs  or  feet  (C,  Fig.  69),  running  from 
the  circumference  of  the  plate  to  the  conical  aperture  A,  in  the 
middle,  by  which  the  truncated  cone  to  be  hammered  upon  is 
molded.  The  object  of  these  feet  is  to  make  the  molding-plate 
strong  enough  to  bear  rough  usage,  and  of  sufficient  weight  to 
prevent  it  from  being  floated  off  the  sand-mold  by  the  weight  of 
the  molten  metal  as  it  is  poured  in,  as  well  as  to  form  steady 
feet  for  the  plate  to  rest  upon  on  the  molding-table. 

The  sand-ring  is  of  strong  hoop-iron,  and  should  fit  easily  and 
truly  on  the  grooved  surface  of  the  molding-plate  next  to  the 
projections  or  tabs. 

When  molding  is  to  be  done,  the  molding-plate  is  placed  in  the 
sand-drawer  or  on  the  table,  grooved  side  upward,  and  on  it  the 
shallow  plaster  model  (from  Y\  to  one  inch  deep,  as  may  be  de- 
sired) (Fig.  67),  in  such  a  position  as  to  bring  the  cone-shaped 
aperture  where  most  strength  is  required  in  the  die.  The  iron 
sand-ring  is  then  put  on  the  molding-plate  (Fig.  68),  and  sand  is 
packed  in  in  the  usual  way.  When  the  packing  is  finished,  the 
iron  ring  full  of  sand,  with  the  molting-plate,  are  turned  upside 
down  (Fig.  69).  The  molding-plate  is  then  removed,  exposing 
the  model,  which  is  withdrawn  by  the  aid  of  a  point  and  hammer 
in  the  usual  way. 

The  mold  having  been  examined,  and  any  loose  particles  of 
sand  blown  out  of  it,  zinc  sufficient  to  barely  fill  the   mold  is 


METALLIC   DIES    AND    COUNTER-DIES.  163 

Fig.  67.  .  Fig.  68. 


Fig.  69. 


Fig.  70. 


Fig.  71. 


Bailey  Die        3-Pound  Zinc 

Ordinary  Die 2VPound  Zinc 

Pearsall  Die  ______  2-Pound  Zinc 


164  MECHANICAL   DENTISTRY. 

poured  in,  the  molding-plate  slightly  heated  is  put  over  the  mold, 
and  the  remaining  zinc  poured  into  the  aperture  to  make  the  cone- 
shaped  end  of  the  die.  Of  course,  if  the  sand-mold  is  over-filled 
with  zinc  in  the  first  instance,  there  will  be  difficulty  in  placing 
the  molding-plate  on  the  sand-mold,  but  this  is  easily  avoided. 

To  make  a  counter-die,  the  molding-plate,  zinc  die,  and  a  coun- 
ter-die ring  are  arranged  as  in  Fig.  70,  sufficient  sand  being 
packed  about  the  die  to  give  the  depth  of  counter-die  required. 

In  use,  the  swaging  of  a  plate  will  be  found  more  certain  and 
accurate,  because  of  the  ease  with  which  heavy  blows  can  be 
struck  on  the  truncated  cone,  and  the  hollow  formed  in  the  center 
of  the  cone  by  the  cooling  of  the  zinc  is  really  a  source  of 
strength,  so  far  as  construction  is  concerned.  The  cone-shaped 
end,  with  the  model  projecting  over  it,  enables  the  die  to  be  held 
in  a  vise  in  such  a  way  that  blows  struck  on  the  palate  or  teeth  of 
the  model  will  not  cause  it  to  slip  in  the  jaws  of  the  vise.  The 
die  thus  has  a  steady  bearing,  forming  a  great  contrast  to  the 
slippery  and  uncertain  hold  of  the  ordinary  form  of  die  when 
placed  in  a  vise  to  be  filed  or  hammered.  It  can  also  be  easily 
and  quickly  turned  and  secured  in  any  desired  position  by  open- 
ing and  instantly  reclosing  the  jaws  of  the  vise,  whereas  neither 
the  Bailey  nor  the  ordinary  form  of  die  can  be  secured  in  a  vise 
with  the  same  certainty,  precision,  or  rapidity. 

Attention  may  also  be  directed  to  the  ease  with  which  blows 
can  be  struck  outside  the  cone  on  the  shoulder  formed  by  the  pro- 
jection of  the  mold,  and  such  blows  are  often  of  the  greatest  ser- 
vice in  certain  cases,  instances  of  which  will  readily  suggest 
themselves. 

The  advantages,  as  summed  up  by  Mr.  Pcarsall,  are  as  follows: 

1 .  The  shallowness  of  the  model  required,  and  the  consequent 
saving  of  time  in  drying  it. 

2.  The  ease  with  which  a  shallow  plaster  model  can  be  re- 
moved from  the  sand  as  compared  with  a  deep  one. 

3.  Saving  in  the  amount  of  zinc  to  be  melted.  As  zinc  deteri- 
orates by  constant  melting,  this  is  important,  and  a  supply  of  zinc 
ought  to  go  further  in  the  constant  use  of  the  smaller  dies. 

4.  The  great  increase  of  strength,  owing  to  the  improved  con- 
struction of  the  die,  aided  by  the  cooling  of  the  zinc. 

5.  The  choice  offered  to  the  workman  in  placing  the  strength 


METALLIC   DIES    AND    COUNTER-DIES.  1 65 

or  blow-resisting  cone,  where  it  is  needed  to  resist  heavy  ham- 
mering. 

6.  The  ease  and  rapidity  with  which  the  new  form  of  die  can  be 
secured  in  any  position  in  the  ordinary  vise. 

7.  The  precision  of  the  blow  secured  by  the  use  of  the  cone- 
shaped  end  of  the  die. 

Diagram  No.  5  (Fig.  71)  shows  sections  of  the  same  model 
used  as  a  die  in  the  new  method,  the  usual  method,  and  that  in- 
vented by  Bailey ;  but  only  a  comparison  of  the  actual  dies  can 
convey  an  adequate  notion  of  the  advantages  of  the  new  form. 

Preparing  Cast  for  Mold,  for  Partial  Dentures. — A  die  is  more 
readily  and  accurately  obtained  from  a  model  for  partial  den- 
tures by  cutting  away  the  plaster  teeth,  as  before  described.  The 
displacement  of  sand  where  the  ridge  overhangs  will,  as  a  general 
thing,  be  unimportant  in  these  cases,  as  the  base  seldom  more 
than  partially  overlaps  the  border. 

When  whiting  or  marble-dust  is  used  in  molding,  it  is  generally 
unnecessary  to  mix  water  with  them,  as  the  moisture  which  they 
absorb  from  the  atmosphere  will  give  to  them  the  proper  con- 
sistency. 

Preparing  and  Pouring  Metal  for  Dies. — Having  obtained  a 
mold  in  either  of  the  ways  mentioned,  the  metal  designed  for  the 
die  should  be  melted  and  poured  carefully  in  upon  the  more 
prominent  portions  on  the  face  of  the  former.  If  the  metal  is 
raised  much  above  its  fusing-point,  or  the  sand  is  quite  damp,  the 
former  should  be  poured  very  slowly  into  the  mold.  It  is  better, 
however,  that  the  sand  should  be  partially  dried  before  pouring 
the  metal,  and  the  die  cast,  on  the  instant  of  the  metal  becoming 
sufficiently  fluid.  An  observance  of  these  precautions  will  pro- 
tect the  sand  from  the  overaction  of  heat,  prevent  ebullition  of 
the  fused  metal  from  the  too  rapid  decomposition  of  the  water  in 
the  sand,  will  give  a  smoother  face  to  the  die,  and  secure  the 
metal  or  metals  from  undue  waste  by  oxidation.  The  opinion  is 
entertained  by  some,  that  greater  shrinkage  of  the  die  occurs 
when  the  metallic  substance  of  which  it  is  composed  is  poured  at 
a  temperature  much  above  its  fusing-point ;  the  fallacy  of  this  is 
made  obvious  by  a  moment's  reflection,  as  a  simple  example  will 
show  that  any  change  affecting  the  face  of  the  die,  as  a  conse- 
quence of  contraction,  can  only  occur  in  the  metal  between  its 


1 66  MECHANICAL    DENTISTRY. 

point  of  solidification  or  liquefaction — for  they  are  identical — and 
its  working  temperature.  Zinc,  for  example,  melts  at  773°.  Now 
if  its  temperature  be  raised  to  12000,  it  will  remain  fluid  until  it 
reaches  773 °,  and  in  passing  through  the  intermediate  degrees  of 
heat,  it  will,  in  obedience  to  gravity,  adapt  itself  perfectly  to  all 
parts  of  the  mold ;  and  this  perfect  continuity  of  the  two  surfaces 
will  remain  unaffected  by  the  contraction  of  the  metal  until  the 
latter  commences  to  "  set "  or  solidify,  after  which,  and  not  until 
then,  the  zinc  begins  to  part  from  the  face  of  the  mold  by  con- 
tracting upon  itself  between  773 °  and  the  mean  temperature  of 
the  air.  So  far  as  any  change,  by  contraction,  in  the  face  of  the 
die  is  concerned,  therefore,  it  is  obviously  immaterial  whether  the 
zinc  be  poured  on  the  instant  of  melting  or  at  12000  ;  the  result 
will  be  the  same  in  either  case. 

The  Franklin  Mold.— The  author  is  indebted  to  Dr.  B.  W. 
Franklin  for  the  following  method  of  securing  metallic  dies  and 
counters  by  a  process  which  greatly  facilitates  the  operation  and 
insures  accurate  and  satisfactory  results  :  "  I  take  all  impressions, 
full  and  partial,  in  plaster.  A  small  hole,  less  than  -Jg-  of  an  inch, 
is  drilled  through  the  highest  point  of  the  palatal  surface  of  the 
impression,  through  cup  and  all ;  into  this  place  two  or  three 
broom  splints,  cutting  them  off  even  with  the  surface  of  the  plas- 
ter, to  allow  any  vapors  to  pass  off.  I  sometimes  smoke  the  sur- 
face of  the  impression.  Around  the  impression  place  sufficient 
putty  to  form  a  ring  the  size  and  height  required  for  the  die.  Into 
this  pour,  at  as  low  heat  as  is  consistent  with  the  mobility  re- 
quired for  sharp  castings,  the  bismuth  alloy  known  as  Sir  Isaac 
Newton  metal,  or,  which  is  better  in  some  respects,  eight  parts 
bismuth  and  four  parts  each  of  tin  and  lead — the  latter  composi- 
tion being  a  little  harder.  If  a  little  judgment  is  exercised  in 
pouring  either  of  the  above  alloys,  a  perfect  die  will  be  secured 
from  moist  plaster  impressions  without  any  drying.  As  the  bis- 
muth is  expansive  and  the  alloy  is  hard  and  somewhat  brittle,  I 
run  only  a  thin  casting,  not  more  than  l/2  of  an  inch  in  thickness, 
over  the  highest  portion  of  the  impression.  I  have  cast-iron  or 
brass  heads  made,  3^4  inches  in  length,  3  inches  in  diameter  at 
the  large  end,  and  2  inches  at  the  other;  the  large  end  is  flat,  and 
well  coated  with  common  tinman's  solder.  This  head  is  heated 
until  the  solder  begins  to  soften  ;  it  is  then  placed  in  a  pan  or  other 
convenient  vessel,  and  the  die,  face  side  up,  is  placed  upon  the 
tinned  surface.     When  the  die  begins  to  melt,  and  perfect  union 


METALLIC    DIES    AND    COUNTER -DIES.  1 67 

is  secured,  cold  water  is  dashed  upon  the  die  and  head ;  and  thus 
we  have  a  sharp  die,  with  an  iron  head,  to  sustain  the  force  of  the 
blow  in  stamping  the  plate,  and  by  this  means  preventing  any- 
spreading  of  the  face  of  the  die  or  liability  of  breaking  in  the 
process  of  swaging. 

"  I  now  take  sheet-lead  of  the  thickness  of  about  No.  24, 
standard  gage,  and  adapt  it  to  the  face  of  the  die  by  means  of  a 
wooden  mallet  or  burnisher,  or  other  convenient  means.  Trim 
the  lead  plate  to  the  size  required  for  the  plate  to  be  stamped ; 
when  the  lead  plate  is  nicely  fitted,  remove  it  carefully  from  the 
die  and  place  it  in  a  ring  or  narrow  molding-flask,  the  palatal  side 
up ;  now  gently  stamp  molding  sand  into  the  plate  and  flask,  up 
level  with  the  edges  of  the  flask ;  then  reverse  the  flask  and  cut 
the  sand  away  clean  for  y2  of  an  inch  or  more  down  to  the  edge  of 
the  lead  plate  all  around.  Around  the  plate  place  a  common 
molding-ring,  sufficiently  large  to  form  the  counter,  which  is 
made  by  pouring  melted  tin  or  lead  (or  any  alloys  of  these  met- 
als) on  to  the  lead  plate,  being  careful  not  to  run  the  metal  so  hot 
as  to  melt  the  lead  plate.  When  the  counter  is  cool  enough  to 
handle,  the  adhering  sand  is  brushed  or  washed  away ;  the  die  is 
then  placed  into  the  bed  or  counter,  and,  with  a  moderate-sized 
hammer,  give  one  or  two  sharp  blows  to  bring  the  die  and  counter 
together.  In  swaging  gold  plates,  two,  three,  or  more  dies  may 
be  required ;  these  may  be  made  either  by  running  the  die  metal 
into  the  impression  (if  not  broken)  or  by  running  into  lead  plates, 
gotten  up  as  before  described,  reserving,  of  course,  the  first  die 
and  counter  for  the  final  swaging  of  the  plate.  I  have  gotten  up 
a  die  and  counter  from  the  impression,  with  the  aid  of  an  assis- 
tant, in  the  foregoing  manner,  in  twelve  minutes.  I  usually  get 
out  my  die  immediately  after  taking  the  impression ;  adapt  a  wax 
or  gutta-percha  plate  to  the  die,  and  get  the  articulation  before 
the  patient  leaves  the  office." 

In  the  act  of  contracting,  the  central  portion  of  the  die,  being 
the  last  to  solidify,  is  gradually  drawn  toward  the  periphery, 
forming,  when  the  contraction  is  completed,  an  excavation  of 
greater  or  less  depth  in  the  center  of  its  base,  a  form  unfavorable 
to  an  equal  distribution  of  the  force  applied  in  swaging,  and 
greatly  increasing  the  danger  of  distorting  the  face  of  the  die  by 
cracking  or  spreading,  especially  when  zinc  is  used.  To  concen- 
trate and  equalize  this  force  is  a  matter  of  the  first  importance. 
The  liability  to  such  an  accident  may,  to  some  extent,  be  avoided 


1 68  MECHANICAL   DEXTISTRY. 

by  placing  on  the  die  a  cone-shaped  cap  of  any  hard  metal,  as  zinc, 
brass,  or  cast-iron.  This,  however,  while  it  provides  against  one- 
sided blows  of  the  hammer,  affords  only  a  partial  remedy,  since 
the  same  danger  of  spreading  the  die  exists,  in  consequence  of  the 
cap  resting  on  the  outer  border  of  the  base  of  the  die,  with  no 
central  bearing  whatever.  To  equalize  the  force  perfectly,  the 
cone-shaped  metal  cap  should  be  incorporated  with,  and  form  part 
of  the  body  of  the  die  itself.  This  is  partly,  if  not  wholly,  accom- 
plished by  Dr.  Franklin's  expedient. 

Counter-dies. — A  counter  to  the  die  is  generally  obtained  di- 
rectly from  the  latter.  The  die  is  placed,  face  upward,  upon  the 
molding-table,  and  sand,  prepared  as  in  molding,  built  up  around 
it,  leaving  only  the  ridge  and  palatal  face  exposed.  It  is  then 
encircled  with  a  cast-  or  sheet-iron  ring  two  or  three  inches  deep, 
its  edge  imbedded  in  the  sand  to  prevent  the  escape  of  the  fluid 
metal ;  into  this  the  metal  for  the  counter  is  poured  until  nearly 
or  quite  full. 

The  metal  commonly  employed  for  the  counter  is  lead,  al- 
though other  substances,  as  tin,  type-metal,  some  of  the  more 
fusible  alloys  hereafter  to  be  mentioned,  etc.,  are  sometimes  em- 
ployed. When  the  counter  is  taken  by  pouring  the  metal  or  met- 
als composing  it  upon  a  die  fusing  at  a  low  heat,  some  caution 
should  be  observed  lest  the  two  pieces  adhere  by  partial  fusion 
of  the  die.  In  such  cases  the  surface  of  the  die  should  be  well 
protected  with  lamp-smoke  or  whiting ;  the  lead  should  be  poured 
at  the  lowest  practical  temperature,  and  the  conduction  of  heat 
facilitated  by  surrounding  the  die  with  a  heavy  cast-iron  box  or 
ring. 

During  the  process  of  forcing  a  plate  into  adaptation  to  the 
form  of  the  mouth  with  swages,  it  not  infrequently  happens  that 
the  marginal  portions  of  the  former  become  wedged  or  immovably 
fixed  between  the  outer  border  of  the  die  and  corresponding  por- 
tions of  the  counter  before  its  central  portion  is  forced  into  con- 
tact with  the  palatal  surface  of  the  former,  thus  rendering  it  diffi- 
cult to  conform  the  plate  accurately  to  the  parts  without  the  appli- 
cation of  sufficient  force  to  deface  or  otherwise  mar  the  form  of 
the  die.  In  such  cases  the  central  portion  of  the  plate  may  be 
first  swaged  with  a  partial  counter,  which  is  made  to  receive  only 
the  palatal  portion  and  upper  surface  of  the  ridge  of  the  die.  This 
method,  as  practised  and  described  by  Dr.  I.  N.  Broomell,  of  the 
Pennsylvania  College  of  Dental   Surgery,  is  as  follows : 


METALLIC    DIES    AND    COUNTER-DIES. 


169 


"  Progressive  Counter-dies. — It  being  desirous,  in  swaging  a 
plate,  to  have  the  palatine  portion  forced  into  position  at  the  be- 
ginning, the  iirst  counter-die  should  be  formed  as  represented  in 
Fig.  72.  To  accomplish  this  the  sand  must  be  built  entirely  over 
the.  ridge,  allowing  only  the  palatine  portion  of  the  die  to  be  ex- 


Fig.  7; 


Fig.  73- 


Fig.  74- 


posed.  The  second  counter-die  should  extend  just  beyond  the 
center  of  the  ridge,  as  shown  in  Fig.  73,  and  the  third  or  final 
counter  may  be  formed  in  the  usual  manner,  see  Fig.  74.  By  the 
judicious  construction  of  this  series  of  counter-dies,  more  satis- 
factory results  are  obtained,  and  much  needless  use  of  the  horn 
mallet  dispensed  with.  It  will  readily  be  observed  that  a  coun- 
ter-die, formed  as  represented  in  No.  i  (Fig.  72),  will  drive  the 
center  of  the  plate  into  position  without  the  usual  resistance  ex- 
perienced in  using  the  ordinary  counter.  The  use  of  No.  ii  (Fig. 
73)  will  gradually  start  the  plate  over  the  ridge,  and  No.  iii  will 
readily  complete  the  process." 


I/O 


MECHANICAL    DENTISTRY. 


As  before  remarked,  preference  is  usually  given  to  lead  in  the 
formation  of  a  counter-die,  mainly  on  account  of  its  greater  soft- 
ness. This  property  in  a  counter  is  practically  important.  In 
the  process  of  forcing  a  metallic  plate  into  adaptation  to  the 
mouth,  partial  displacement  or  yielding  of  either  the  die  or 
counter,  or  of  both,  necessarily  occurs,  and  it  is  scarcely  necessary 
to  remark  that  whatever  change  of  form  is  produced  should  take 
place  wholly  in  the  counter,  otherwise  deformity  of  the  die  must 
ensue. 

Essential  Properties  of  a  Die. — There  are  certain  properties 
which  it  is  indispensable  that  a  metallic  die  should  possess  in 
order  to  answer  fully  the  requirements  of  the  dentist. 

1.  A  die  should  be  sufficiently. hard  to  resist  any  necessary  force 
applied  to  it  in  stamping  the  plate  without  suffering  any  material 
change  in  the  form  of  its  face,  by  which  latter  term  is  meant  that 
portion  of  the  die  with  which  the  plate  is  brought  in  contact. 
This  property  is  most  indispensable  in  those  cases  where  the  arch 
of  the  mouth  is  very  deep,  the  rugae  prominent  and  sharply  de- 
fined, and  where  the  alveolar  ridge  is  marked  by  angular  and 
abrupt  prominences  and  depressions.  In  such  cases,  if  the  die  is 
not  sufficiently  resistant,  the  points  most  prominent  upon  its  face 
will  be  bruised  or  battered  down,  while  the  plate  will  fail  to  be 
forced  perfectly  into  the  cavities  or  depressions,  and  its  coapta- 
tion to  the  mouth,  to  that  extent,  rendered  faulty.  The  case  in 
which  a  less  degree  of  hardness  is  admissible  is  where  the  arch  of 
the  mouth  is  broad  and  shallow,  the  rugae  imperfectly  defined,  and 
the  ridge  regular  and  symmetrical.  The  conformation  of  the 
mouth,  therefore,  will,  in  respect  to  the  property  of  hardness,  ad- 
mit of  some  latitude  in  the  choice  of  the  metal  or  alloy  employed 
in  the  formation  of  a  die. 

2.  Another  important  property  of  a  metallic  die  is  non-contrac- 
tion, so  far,  at  least,  as  this  is  attainable.  Inasmuch  as  the  suc- 
cessful adaptation  of  the  plate  depends,  in  a  great  measure,  upon 
an  accurate  representation  of  the  precise  form  of  the  mouth  in  the 
die,  it  is  of  the  first  importance  that  the  latter,  other  requisites 
being  secured,  should  be  composed  of  some  metal  or  metals  hav- 
ing the  least  possible  contraction  in  cooling.  Contraction  is,  in 
varying  degrees,  common  to  all  metals  exposed  to  a  decreasing 
temperature,  and  it  is  impossible,  therefore,  to  obtain  a  perfectly 


METALLIC   DIES    AND    COUNTER-DIES.  171 

faultless  copy  of  the  mouth  in  metal.  Fortunately,  as  well  for 
the  expert  as  the  unskilled  manipulator,  the  unavoidable  shrink- 
age incurred  is  partially  or  wholly  compensated  for,  by  the  ex- 
pansion of  the  plaster  model  and  the  yielding  condition  of  the 
soft  tissues  of  the  mouth,  but  under  no  circumstances  should  the 
accommodation  afforded  by  the  condition  last  mentioned  encour- 
age negligence  or  unskilfulness  in  the  use  of  all  available  means 
necessary  to  secure  the  most  accurate  adaptation  of  the  base. 
Ordinarily,  a  moderate  degree  of  contraction  will  not  materially 
impair  the  fit  of  a  plate ;  on  the  contrary,  in  the  case  of  the  upper 
jaw,  it  sometimes  favors  its  adhesion  and  retention  in  the  mouth. 
Cases,  on  the  other  hand,  frequently  occur  where  the  least  prac- 
ticable amount  of  shrinkage,  even  at  the  partial  sacrifice  of  other 
properties,  becomes  indispensable  in  the  die. 

3.  A  third  important  requisite  of  a  die  is  fusibility.  Aside  from 
the  convenience  incident  to  the  use  of  metals  which  fuse  at  a  low 
heat,  there  is  another  consideration  favoring  this  property  of  more 
practical  importance.  It  is  well  known  that  all  metals  expand  by 
heat  and  contract  by  cold.  In  obedience  to  this  law,  metals  fus- 
ing at  a  high  heat  suffer  a  greater  aggregate  contraction  than 
those  melting  at  a  lower  temperature,  and,  as  between  two  metal- 
lic bodies  of  equal  dimensions,  liquefying  at  different  tempera- 
tures, the  difference  in  contraction  will  correspond  exactly  with 
the  difference  in  the  number  of  degrees  through  which  each  passes 
from  the  point  of  solidification  to  the  mean  temperature  of  the  air, 
allowance  being  made  for  the  difference  in  their  ratios  of  contrac- 
tion. The  difference  in  the  contraction  will  be  somewhat  modified 
by  that  in  their  ratio  of  contraction,  but  it  will  always  be  found 
that  the  more  fusible  metals  have  the  least  aggregate  shrinkage 
whenever  any  considerable  disparity  exists  between  their  fusing- 
points.  It  is  in  accordance  with  the  principles  here  set  forth  that 
the  more  fusible  alloys,  some  of  which  melt  at  remarkably  low 
temperatures,  are  employed  whenever  it  is  important  to  obtain  a 
die  as  nearly  the  exact  counterpart  of  the  model  as  possible. 

4.  Finally,  a  die  should  be  sufficiently  cohesive  to  resist  the  re- 
peated blows  of  a  heavy  hammer  without  parting  or  cracking. 
Many  metals,  as  antimony,  bismuth,  etc.,  in  other  respects  suit- 
able for  dies,  are  objectionable  on  account  of  brittleness.  But  it 
must  not,  therefore,  be  inferred  that  all  metals  that  are  denom- 


172  MECHANICAL   DENTISTRY. 

inated  brittle  are  inadmissible  for  this  purpose ;  for  zinc,  which  in 
its  ordinary  condition  is  ranked  as  a  brittle  metal,  and  type-metal, 
which  is  always  so,  are  in  no  danger  of  being  forced  asunder  or 
of  suffering  displacement  when  in  the  compact  form  of  a  die,  pro- 
vided the  force  used  in  swaging  is  judiciously  applied,  or  proper 
form  and  sufficient  depth  are  given  to  the  body  of  the  die. 

To  recapitulate  briefly :  A  die  should  be  formed  of  some  metal 
or  alloy  that  has  a  surface  hardness  sufficient  to  resist  compres- 
sion ;  that  fuses  at  a  low  temperature ;  that  does  not,  in  any  mate- 
rial degree,  contract  in  the  act  of  cooling,  and  whose  particles 
adhere  with  sufficient  cohesive  force  to  maintain  perfectly  its  in- 
tegrity of  form  under  the  hammer.  Any  one  or  two  of  these 
properties  are  readily  attainable  in  the  same  die,  but  no  one 
known  metal  or  alloy  combines  all  of  them  perfectly.  Thus  either 
cast-iron,  brass,  bronze,  or  cannon  metal  would  form  an  excellent 
material  in  respect  of  surface  hardness,  and  in  the  compact  form 
of  a  die  would  be  sufficiently  cohesive,  but  few  enjoy  convenient 
facilities  for  melting  them ;  besides,  their  great  contraction,  con- 
sequent upon  their  high  fusing-point,  would  render  their  employ- 
ment entirely  inadmissible.  Again,  certain  alloys,  as  those  com- 
posed of  lead,  tin,  and  antimony  or  bismuth,  are  eminently  suit- 
able on  account  of  their  ready  fusibility  and  comparative  exemp- 
tion from  shrinkage,  but  they  gain  these  properties  at  the  expense 
of  that  degree  of  hardness  necessary  to  resist  compression.  Tin, 
in  its  uncombined  state,  is  ordinarily  sufficiently  fusible,  tena- 
cious, and  non-contractile,  but  is  too  soft  and  yielding  when 
forcibly  compressed.  Antimony  and  bismuth  are  sufficiently 
hard,  fusible,  and  non-contractile,  but  are  objectionable  on  the 
score  of  extreme  brittleness. 

Any  metallic  substance  that  combines  most  perfectly  the  sev- 
eral properties  referred  to  is,  therefore,  best  adapted  to  the  neces- 
sities of  the  mechanical  operator,  and  experience  has  almost  uni- 
versally accorded  preeminence  in  this  respect  to  zinc.  It  presents 
a  more  resistant  surface  to  the  blow  of  a  hammer  than  either  cop- 
per  or  brass,  three  times  more  so  than  that  of  tin,  and  more  than 
double  that  of  type-metal.  As  it  usually  occurs  in  commerce  it 
may  be  classed  as  a  brittle  metal,  but  when  annealed  it  is  tough 
and  malleable.  Tt  melts  at  a  heat  (7730)  which  may  be  readily 
commanded,  and  contracts  but  little  in  cooling.     The  late  Pro- 


METALLIC    DIES    AND    COUNTER-DIES. 


173 


fessor  Austen  demonstrated  by  actual  experiments  that  an  aver- 
age-sized zinc  die  measuring  two  inches  transversely  contracts 
if  o"o"  °f  an  mc^  from  outside  to  outside  of  the  alveolar  ridge,  being 
equivalent  in  thickness  to  three  leaves  of  this  volume.  Professor 
Austen  remarks:  "  In  the  first  case  (upper  jaw)  the  plate  would 
'  bind,'  and  if  the  ridge  were  covered  by  an  unyielding  mucous 
membrane  it  would  prevent  accuracy  of  adaptation.  In  the  sec- 
ond case  (under  jaw)  the  plate  would  have  too  much  lateral 
'  play/  and  consequently  lack  stability.  Again,  in  a  moderately 
deep  arch,  say  y2  of  an  inch  in  depth,  the  shrinkage  between  the 
level  of  the  ridge  and  the  floor  of  the  palate  will  be  nearly  y^-q-q — 
rather  more  than  one  leaf.  In  the  deepest  arches  this  shrinkage 
becomes  a  serious  difficulty ;  in  the  shallower  cases  it  is  not  of 
much  moment,  as  there  is  no  mouth  so  hard  as  not  to  yield  the 

T0V0   or  TOT 0   of  an  inch/' 

As  before  stated,  a  moderate  degree  of  shrinkage  in  the  die 

may,  in  certain  conditions  of  the  mouth,  practically  favor  the  ad- 
hesion and  permanent  retention  of  a  plate  applied  to  the  upper 
jaw.  The  conditions  alluded  to,  and  which  prevail  in  a  greater 
or  less  degree  in  all  cases,  are  soft  and  yielding  ridge,  and  com- 
paratively hard  and  unimpressible  palate.  Now,  if  in  the  first 
instance  the  plate  is  swaged  into  uniform  contact  with  all  parts 
of  the  jaw,  it  will  be  readily  perceived  that  if  pressure  is  made 
over  the  ridge  on  one  side  the  latter  will  yield,  while  the  central 
portion  of  the  plate,  meeting  with  a  fixed  point  of  resistance  at 
the  floor  of  the  palate,  will  "  ride  "  upon  the  latter,  and  thus  throw 
the  plate  from  the  ridge  on  the  opposite  side  of  the  jaw.  If,  how- 
ever, a  space  equal  to  one  or  two  thicknesses  of  the  plate  exists 
between  the  latter  and  the  roof  of  the  mouth,  as  a  consequence  of 
contraction  in  the  die,  the  plate,  as  it  is  carried  against  the  palate 
in  the  act  of  exhausting  the  air  from  beneath  it,  will,  at  the  same 
time,  forcibly  compress  the  ridge,  securing  thereby  a  more  resis- 
tant basis  along  the  border,  and  providing  more  certainly  against 
displacement  of  the  base  on  the  application  of  forces  brought  to 
bear  upon  it  in  mastication. 

The  extent  to  which  the  shrinkage  of  a  die  may  be  admitted  in 
any  given  case  will  depend  partly  upon  difference  in  the  condi- 
tions heretofore  mentioned  in  the  soft  parts  of  the  mouth,  and  in 
part,  also,  upon  the  general  configuration  of  the  jaw.     In  a  me- 


174  MECHANICAL    DENTISTRY. 

dium-sized  mouth,  with  a  depth  of  say  y2  of  an  inch  to  the  arch,  a 
moderately  soft  ridge  and  resisting  palate,  the  shrinkage  incident 
to  zinc  will  be  unimportant,  and  in  many  cases  will  be  advantage- 
ous. If,  however,  the  vault  is  very  deep,  even  though  there  be  a 
yielding  ridge,  the  unavoidable  contraction  of  a  zinc  die  will 
throw  the  plate  so  far  from  the  arch  as  to  render  it  difficult  for  the 
patient  to  exhaust  the  atmosphere  from  between  it  and  the  floor 
of  the  palate,  and  even  when  the  latter  is  practicable,  the  plate 
will  bind  with  such  force  upon  the  outer  border  of  the  ridge  as  not 
only  to  produce  pain  and  irritation  of  the  compressed  parts,  but 
the  resistance  afforded  at  these  points  will  be  sufficient,  in  many 
cases,  to  break  up  the  adhesion,  and  force  the  plate  from  the  pal- 
ate. Again,  as  an  extreme  case,  if  the  ridge  and  palate  are  some- 
what uniformly  unyielding,  and  the  palatal  vault  is  at  the  same 
time  very  deep,  a  zinc  die  can  only  be  made  available  in  bringing 
the  base  as  nearly  into  adaptation  as  possible,  after  which  the 
operation  may  be  completed  with  a  swage  having  a  less  degree  of 
shrinkage,  and  which,  as  a  mere  finishing  die,  need  not  neces- 
sarily be  so  hard  as  zinc. 

In  conforming  a  plate  to  the  lower  jaw,  the  die  should  be  as 
free  as  possible  from  contraction  in  all  cases.  The  greatest 
shrinkage  in  such  cases  will  be  between  the  posterior  extremities 
of  the  ridge,  giving  too  much  lateral  play  to  the  plate ;  in  addi- 
tion to  which  the  posterior  and  inner  edge  of  the  base,  projecting 
outward  from  the  ridge,  will  obstruct  the  free  action  of  the 
tongue,  while  the  latter  will  tend  to  lift  it  from  the  ridge  and  ren- 
der it  unstable.  These  conditions  may  be  partially  remedied  by 
turning  the  edge  of  the  plate  in  against  the  ridge  with  pliers ;  but 
this  expedient  should  never  be  resorted  to  in  any  case  whenever 
it  is  practicable  to  secure  a  correct  adaptation  by  swaging. 

In  all  cases  in  which  a  zinc  die  fails  to  bring  the  plate  into 
proper  adaptation  to  the  parts,  either  of  the  following  metallic 
compounds  may  be  used  to  complete  the  process  after  partial 
stamping  with  zinc. 

Type-metal. — Lead,  five  parts;  antimony,  one  part.  Fuses  at 
5000  ;  contraction  less  than  one-half  that  of  zinc ;  more  compres- 
sible than  the  latter  and  very  brittle. 

Babbitt  or  Anti-friction  Metal. — Copper,  three  parts ;  anti- 
mony, one  part;  tin,  three  parts.     First  fuse  the  copper,  and  then 


METALLIC    DIES    AND    COUNTER-DIES. 


175 


add  the  antimony  and  tin.  Melts  at  a  moderately  low  heat;  con- 
tracts but  little ;  is  brittle,  but  may  be  rendered  less  so  by  adding 
tin. 

Zinc,  four  parts ;  tin,  one  part.  Fuses  at  a  lower  heat,  contracts 
less  in  cooling,  and  has  a  less  surface  hardness  than  zinc. 

Tin,  five  parts ;  antimony,  one  part.  Melts  at  a  lower  heat  than 
either  of  the  preceding  alloys;  contracts  but  slightly  in  cooling; 
is  harder  than  tin  and  sufficiently  adhesive.  It  is  readily  oxid- 
ized and  should  be  poured  as  soon  as  melted. 

Fusible  Alloys. — The  following  tabular  view  of  the  more  fusi- 
ble alloys,  the  respective  properties  of  which  are  deduced  from 
actual  experiments,  was  given  by  Professor  Austen  in  a  paper  on 
"  Metallic  Dies."  *  Zinc  is  introduced  into  the  table  for  the  pur- 
pose of  comparison. 


1 .  Zinc,    

2.  Lead,  2,  Tin,   1 

3.  Lead,   1,  Tin,  2,    

4.  Lead,  2,  Tin,   3,  Antimony,   1,    

5.  Lead,   5,  Tin,  6,  Antimony,   1,    

6.  Lead,   5,  Tin,  6,  Antimony,   1,   Bismuth,   3, 

7.  Lead,   1,  Tin,   1,  Bismuth,    1,    

8.  Lead,  5,  Tin,   3,  Bismuth,  8,    

9.  Lead,  2,  Tin,   1,  Bismuth,  3,    


Melting- 

Contrac- 

Hardi- 

point. 

tility. 

ness. 

770° 

.OI366 

.Ol8 

440 

.00633 

.050 

340 

.OO50O 

.040 

420 

•OO433 

.026 

320 

.00566 

•035 

3OO 

.00266 

.030 

250 

.OO066 

.042 

200 

.00200 

•045 

200 

.OOI33 

.048 

Brittle- 
ness. 


In  commenting  on  the  preceding  table,  Professor  Austen  ob- 
serves :  "  The  last  column  contains  an  approximate  estimate  of 
the  relative  brittleness  of  the  samples  given.  .  As  in  the  other  col- 
umns, the  low  numbers  represent  the  metals,  so  far  as  this  prop- 
erty is  concerned,  most  desirable.  Those  marked  below  five  are 
malleable  metals ;  those  above  five  are  brittle  ;  zinc,  marked  five, 
separates  these  two  classes,  and  belongs  to  one  or  the  other,  ac- 
cording to  the  way  in  which  it  is  managed."  Allusion  is  here 
made  to  the  process  of  annealing  zinc,  which  has  already  been 
alluded  to  when  considering  the  latter  metal  in  the  former  part  of 
the  work.  The  special  method  employed  is  thus  described  by 
the  author  already  quoted :  "  The  simplest  way  to  anneal  a  zinc 
die  is  to  place  it  in  the  melting  ladle  with  about  a  tablespoonful 
of  water,  removing  it  in  thirty  seconds  after  the  water  has  boiled 


*  American  Journal  of  Dental  Science,  vol.  vi,  page  367. 


I76  MECHANICAL   DENTISTRY. 

away.  If  the  fire  is  a  very  hot  one,  remove  it  immediately  on  the 
disappearance  of  the  water.  It  will  often  happen  that  the  die  is 
annealed  in  the  process  of  taking  the  counter-die.  This  will  more 
certainly  occur  when  Nos.  7,  8,  or  9  (see  table),  are  used  for  the 
counter.  For  example,  take  tin,  using  a  mass  twice  the  size  of 
the  die;  should  it  be  heated  to  5400  (ioo°  above  melting-point), 
it  would  not,  allowing  for  loss  of  heat  by  radiation  and  contact 
with  the  cast-iron  ring  (if  one  be  used),  heat  the  zinc  beyond 
3300.  Lead,  cast  as  cool  as  it  could  possibly  be  poured,  unless  in 
a  very  heavy  ring  (such  as  a  '  cart-wheel  box  '),  or  in  quantity  too 
small  for  a  well-shaped  Counter,  would  be  apt  to  raise  the  zinc  at 
least  400°,  and  so  impair  its  malleability,  whilst,  if  poured  as  hot 
as  many  are  in  the  habit  of  doing,  the  zinc  will  remain  as  brittle 
as  when  first  cast." 

The  Parker  Swaging  Device. — This  device  for  swaging  dental 
plates  (Fig.  75)  consists  of  two  parts :  First,  a  cup  made  of  cast- 
iron  from  3  to  3^2  inches  in  diameter,  and  i1/*  inches  in  depth, 
and  a  "  plunger  "  or  "  follower,"  turned  to  fit  the  inside  of  the  cup, 
with  a  concussion  block  in  the  upper  end.  The  lower  edge  of  the 
plunger  is  a  concave  flange  so  formed  that  when  forced  into  the 
cup  the  contents  of  the  cup  will  be  forced  toward  a  common 
center.  Shot  is  here  employed  as  the  counter,  the  finest  obtain- 
able, No.  12  being  the  best. 

In  using  this  device,  first  prepare,  in  any  suitable  manner,  a 
thin  metallic  model,  ]/\  of  an  inch  in  thickness  over  the  palatine 
arch  is  sufficient ;  over  this  "  rough  swage  "  the  metallic  blanks 
with  a  horn  mallet,  or  in  any  suitable  way,  until  the  edges  are 
brought  close  to  the  model ;  this  is  to  prevent  the  shot,  or  other 
material  used,  from  passing  under  the  plate.  Wrap  the  model 
and  plate  with  a  few  thicknesses  of  tough  manilla  tissue-paper; 
this  will  keep  the  shot  from  getting  under  the  plate,  and  prevent 
"  leading."  Fig.  76  shows  the  device  open,  ready  to  have  the 
model  introduced. 

When  this  is  done,  pour  a  layer  of  shot  into  the  cup,  sufficient 
to  give  the  model  an  even  bearing;  place  the  model  and  plate  in 
the  center,  and  fill  up  with  shot  until  both  are  just  covered. 
Now  insert  the  plunger,  and  be  sure  that  it  rests  squarely  upon  the 
shot,  for  if  it  pinches  or  binds  in  the  cup,  and  is  then  hammered 
upon,  it  will  be  almost  certain  to  fracture  the  cup,  while  if  the 


METALLIC   DIES    AND    COUNTER-DIES. 


177 


follower  rests  entirely  on  the  material  in  the  cup,  it  will  be  driven 
downward  and  inward,  no  lateral  strain  developing.  The  cup 
must  stand  upon  an  anvil  or  some  other  smooth,  solid  surface, 
while  the  hammering  is  being  done.  Any  weight  of  hammer  may 
be  used — the  heavier  the  hammer  the  fewer  the  blows  necessary 
— until  the  shot  is  thoroughly  condensed ;  then  open  and  pour  the 
contents  out  of  the  cup.  If,  on  examination,  the  edges  of  the 
plate  are  not  in  close  contact  with  the  model,  bend  them  down 
carefully  with  pliers,  replace  them  in  the  cup  and  reswage  until 

Fig.  76. 


Fig.  75 


the  plate  fits  the  model  perfectly.  The  pressure  is  so  evenly  dis- 
tributed that  no  amount  of  hammering  will  distort  the  die,  and  if 
desirable,  after  the  plate  is  well  fitted  to  the  metallic  model,  it 
may  be  swaged  over  the  original  plaster  cast. 

This  method  can  also  be  employed  to  good  advantage  in  re- 
swaging  an  ill-fitting  plate,  with  the  teeth  on  or  off,  by  securing  a 
new  impression,  trimming  or  carving  model  as  the  case  may  indi- 
cate ;  then,  adjust  plate  to  the  plaster  model  and  swage  upon  it. 


CHAPTER  XVI. 

PARTIAL  DENTURES  RETAINED  IN  THE  MOUTH  BY  MEANS  OF 

CLASPS. 

Introductory  Remarks. — The  almost  unlimited  modifications 
in  the  form  of  substitutes  designed  to  supply  the  loss  of  a  portion 
only  of  the  natural  teeth,  and  the  difficulties  oftentimes  incident 
to  a  harmonious  arrangement  of  the  teeth  of  replacement,  as  well, 
also,  as  the  impracticability  of  always  securing  a  perfectly  satis- 
factory and  efficient  antagonism  or  closure  of  the  artificial  with 
the  natural  organs,  frequently  surround  this  process  with  peculiar 
embarrassments,  and  often  render  their  successful  application 
extremely  difficult.  They  will,  accordingly,  be  found  to  demand 
of  the  operator  the  exercise  of  greater  skill,  ingenuity,  and  dis- 
crimination than  are  usually  required  of  him  in  the  construction 
and  application  of  entire  dentures. 

Certain  general  and  characteristic  forms  of  substitutes  of  the 
kind  under  consideration  derive  their  distinctive  character  from 
the  means  employed  in  fixing  or  retaining  them  in  the  mouth. 
These  means  of  retention  may  be  classified  as:  (i)  Clasps  at- 
tached to  the  remaining  natural  teeth ;  (2)  atmospheric  pressure 
and  adhesion. 

Observations  on  the  Use  of  Clasps. — Clasps  or  metallic  bands 
have  been  long  and  very  generally  employed  as  a  means  of  retain- 
ing parts  of  sets  of  teeth  in  the  mouth,  and  are  still  used,  to  a 
limited  extent,  for  that  purpose  by  many  practitioners.  When 
these  appliances  are  skilfully  adjusted,  and  all  the  conditions  per- 
taining to  the  mouth  and  remaining  natural  teeth  are  favorable  to 
their  application,  they  afford  a  certain,  permanent,  and  satisfac- 
tory means  of  supporting  partial  dentures,  and  may  be  employed, 
under  such  circumstances,  with  comparative  safety  to  the  natural 
organs.  When  it  is  remembered,  however,  that  in  a  lamentably 
large  proportion  of  cases,  clasps  are  carelessly  or  unskilfully 
formed  and  fitted  to  the  teeth ;  that  the  organs  of  support  are 
often  indiscriminately  selected,  and  are  neither  adapted  in  form, 

178 


PARTIAL    DENTURES    RETAINED    BY    CLASPS. 


179 


situation,  or  structure  for  such  uses ;  and  that  they  are  frequently- 
diseased  and  insecurely  attached  to  the  jaw,  or  are  mutilated  for 
the  reception  of  clasps,  we  can  readily  understand  to  what  unlim- 
ited extent  this  method  is  subject  to  abuses.  In  fact,  few  other 
special  processes  in  mechanical  practice  have  been  so  fruitful  of 
evil  as  that  under  consideration,  and  the  opprobrium  which  but 
too  justly  attaches  to  it  in  professional  as  well  as  popular  estima- 
tion, is  chargeable  more  properly  to  bad  faith  and  unskilfulness  on 
the  part  of  the  operator,  and  to  want  of  necessary  attention  to  the 
cleanliness  of  the  substitute  and  the  organs  of  the  mouth  on  the  part 
of  the  patient,  than  to  any  inherent  unsuitableness  of  the  method 
itself.  Nevertheless,  it  must  be  admitted  that,  under  the  most 
favorable  circumstances,  the  teeth  clasped  are  not  wholly  exempt 
from  liability  to  injury,  and  this  circumstance  in  itself  renders  it 
the  more  imperative  that  the  process  should  be  surrounded  by 
all  the  safeguards  that  skill  and  ingenuity  can  devise. 

The  opinion,  at  one  time  current,  that  the  injury  inflicted  upon 
the  teeth  by  clasps  was  mainly  the  result  of  mechanical  action, 
has  given  place  to  the  more  defensible  view  that  the  causes  con- 
cerned in  its  production  are  chiefly  of  chemical  origin.  Thus, 
the  secretions  of  the  mouth,  with  particles  of  food  being  retained 
between  the  clasp  and  the  tooth  for  a  sufficient  period  of  time, 
and  exposed  to  the  favoring  conditions  of  warmth  and  immo- 
bility, suffer  a  process  of  putrefactive  decomposition  by  which 
acids  are  eliminated,  and  which,  in  their  nascent  state,  act  with 
perceptible  energy  upon  the  bone  constituents  of  the  tooth,  pro- 
ducing disintegration  and  ultimate  decay.  The  rapidity  and  ex- 
tent of  this  action  will  depend  much  upon  the  nature  and  quan- 
tity of  the  acids  present ;  the  structural  characteristics  and  vital 
resistance  of  the  teeth ;  the  mechanical  execution,  adaptation,  and 
composition  of  the  plate ;  and  the  personal  habits  of  the  patient 
with  respect  to  cleanliness. 

The  most  usual  seat  of  structural  disorganization  in  these  cases 
is  at  the  neck  of  the  tooth,  where  the  enamel  is  thinnest,  and  is 
sometimes  limited  to  a  circumscribed  spot,  but  oftener  extends 
on  a  line  with  the  gum,  involving  nearly  or  quite  all  of  that  part 
of  the  neck  of  the  tooth  embraced  by  the  clasp.  At  first  the 
enamel  becomes  bleached  and  softened  as  though  macerated,  and 
is  ordinarily  very  sensitive  to  both  chemical  and  mechanical  irri- 


l80  MECHANICAL   DENTISTRY. 

tants.  With  a  continuance  of  the  cause,  the  superficial  portions 
of  the  affected  parts  become  more  and  more  thoroughly  disin- 
tegrated, and  sooner  or  later  assume  the  open  form  and  charac- 
teristics of  ordinary  decay.  If,  as  was  formerly  supposed,  decay 
or  solution  of  tooth-bone  in  these  cases  resulted  from  mechanical 
attrition,  or  wearing  away  of  the  enamel,  the  injury  would  be 
inflicted  at  points  distant  from  the  neck  of  the  tooth  where  the 
clasp  lies  in  more  direct  and  immediate  contact  with  the  pro- 
tuberant portions  of  the  crown ;  but  we  find  that  decay,  from  this 
cause,  is  not  only  of  infrequent  occurrence  at  such  points,  but,  on 
the  contrary,  the  enamel  here  is  frequently  found  condensed  and 
polished  by  the  mechanical  action  of  the  clasp.  Certain  condi- 
tions of  the  plate  and  clasp  undoubtedly  favor  mechanical  action 
and  accelerate  the  destruction  of  the  tooth ;  as  where  the  clasp 
bears  unequally  with  sharp  and  unfinished  edges  upon  the  tooth, 
or  where  the  base  is  faulty  in  its  adaptation  to  the  mouth,  ad- 
mitting, by  its  mobility,  of  irregular  traction  or  pressure  upon 
the  organs  of  support.  Whenever  the  artificial  appliance  is  thus 
unskilfully  constructed  and  applied,  and  free  interspaces  are.  fur- 
nished for  the  lodgment  and  retention  of  particles  of  food,  and 
the  teeth  clasped  are  defective  in  structure,  and  we  have  con- 
joined with  these,  an  utter  disregard  of  cleanliness  in  regard  to 
the  substitute  and  remaining  natural  teeth,  the  destruction  of  the 
latter  is  certain,  rapid,  and  generally  irretrievable. 

The  Teeth  to  which  it  is  most  Proper  to  Attach  Clasps. — The 
utility,  comfort,  and  appearance  of  a  partial  set  of  artificial  teeth 
in  the  mouth  will  depend  much  upon  the  fitness  of  the  natural 
organs- selected  for  the  purpose  of  support.  "A  clasp,"  says 
Professor  Harris,  "  should  never  be  applied  to  a  loose  tooth,  or  to 
one  situated  in  a  diseased  socket,  or  which  is  so  much  affected  by 
caries  as  to  render  its  perfect  restoration  and  permanent  preser- 
vation impracticable,  and  when  none  but  such  can  be  had,  the 
proper  course  to  pursue  is  to  extract  every  tooth  in  the  jaw,  and 
replace  the  loss  of  the  whole  with  an  entire  denture.  The  appli- 
cation of  clasps  to  diseased  or  loose  teeth,  always  aggravates  the 
morbid  condition  of  the  parts,  and  causes  the  substitute  which 
they  sustain  to  become  a  source  of  annoyance  to  the  patient.  Be- 
sides, such  teeth  can  be  retained  in  the  mouth  only  for  a  short 
time,  and  when  they  give  way,  the  artificial  appliance  becomes 


PARTIAL   DENTURES    RETAINED    BY    CLASPS.  l8l 

useless,  and  even  while  it  is  worn,  it  is  not  held  firmly  in  place, 
but  is  moved  up  and  down  by  the  action  of  the  lips  and  tongue,  so 
that  its  presence  can  hardly  escape  observation  from  the  most 
casual  observer."* 

Teeth,  also,  that  are  too  short  to  admit  of  sufficient  breadth  to 
the  clasp  to  impart  stability  to  the  substitute,  and  those  that 
stand  very  irregularly  in  the  arch,  rendering  it  difficult  for  the 
patient  to  apply  and  remove  the  appliance,  are  unsuitable  as 
organs  of  support. 

In  reference  to  the  individual  classes  of  teeth,  it  may  be  ob- 
served that  the  incisors,  both  as  regards  form  and  situation,  are 
inadmissible  for  clasping,  and  are,  therefore,  never  used  for  this 
purpose.  The  cuspid  teeth,  likewise,  being  placed  conspicuously 
in  the  front  part  of  the  mouth,  cannot  be  securely  embraced  with- 
out manifest  exposure  of  the  clasp ;  besides,  the  conical  form  of 
these  teeth  makes  the  use  of  a  very  slender  clasp  indispensable ; 
hence,  these  teeth  are  rarely  employed,  and  may  only  be  used 
when,  in  the  judgment  of  the  operator,  the  necessities  of  the 
patient  for  the  time  being  seem  to  require  it. 

Either  the  anterior  or  the  second  molars,  when  sound  and  firm, 
offer,  in  respect  of  their  general  conformation  and  position  in  the 
arch,  the  most  desirable  and  efficient  support  for  parts  of  sets  of 
teeth.  The  crowns  of  these  teeth  generally  afford  ample  breadth 
to  the  clasp ;  have  nearly  parallel  walls ;  and  furnish,  by  the 
strength  and  immobility  of  their  attachments  to  the  jaw,  the 
greatest  security  to  the  artificial  appliance.  The  anterior  molars 
are  preferable  where  these  are  remaining  in  good  condition,  or 
are  susceptible  of  being  properly  restored  and  preserved  if  dis- 
eased or  carious. 

Of  the  bicuspids,  the  posterior  are  to  be  selected,  if  practicable, 
as  these  better  favor  the  concealment  of  the  clasps ;  to  effect 
which  more  perfectly,  in  the  use  of  either  the  first  or  second 
bicuspids,  it  will  be  sufficient  in  many  cases  to  embrace  only  the 
posterior  half  of  the  crown. 

The  third  molars,  or  wisdom  teeth,  will  seldom  admit  of  the 
application  of  clasps,  as  the  crowns  of  these  teeth  are  usually  very 
short  and  cone-shaped,  the  walls  converging  abruptly  from'  the 
gum ;  besides,  the  retractive  forces  applied  to  the  anterior  teeth  of 

*"  Principles  and  Practice  of  Dental  Surgery,"  page  717. 


1 82  MECHANICAL   DENTISTRY. 

the  substitute  would,  on  account  of  the  increased  leverage  con- 
sequent upon  the  extension  of  the  plate  back  to  these  teeth,  tend 
either  to  disengage  the  clasps  or  produce  displacement  of  the 
teeth  to  which  they  are  applied. 

In  supplying  the  loss  of  the  inferior  incisors,  the  appliance 
should,  as  a  general  thing,  be  attached  either  to  the  anterior  or 
posterior  bicuspids,  as  these  teeth  stand  more  nearly  vertical  in 
the  arch.  In  fixing  partial  lower  dentures,  it  will  be  sufficient  to 
simply  provide  against  mobility  of  the  base,  as  they  are  favored 
rather  than  opposed,  as  above,  by  gravitation. 

The  replacement  of  the  inferior  teeth  posterior  to  one  or  both 
bicuspids,  however,  is  more  frequently  demanded ;  in  which  case 
it  is  customary  to  attach  the  clasps  to  the  teeth  immediately  in 
front  of  and  adjoining  the  vacuities  on  each  side.  It  will  not, 
however, be  necessary  to  attach  clasps  in  these  cases  whenever  the 
edentulous  portions  of  the  jaw  present  a  distinctly  scooped  form 
or  marked  concavity  of  outline,  forming  a  kind  of  bed  for  the 
plate.  If,  on  the  other  hand,  the  ridge  falls  back  with  a  tolerably 
uniform  inclination  from  the  teeth  in  front,  with  no  sufficient  ele- 
vation at  the  base  of  the  coronoid  process,  it  may  become  neces- 
sary to  provide  against  backward  displacement  of  the  substitute 
by  attaching  clasps,  as  before  stated,  to  the  teeth  immediately  in 
front.  In  any  case,  if  the  third  molars  remain,  partial  or  stay 
clasps  may  be  attached  to  each  heel  of  the  plate,  and  so  adjusted 
as  to  rest  against  the  anterior  face  of  these  teeth,  obviating  en- 
tirely the  necessity  of  clasps  in  front. 

Separation  of  the  Teeth  for  the  Reception  of  Clasps. — The 
practice  of  separating  the  teeth  with  the  file  to  provide  for  the  ap- 
plication of  clasps  should  always  be  avoided,  since  the  liability  of 
the  teeth,  thus  denuded  of  enamel,  to  decay  is  greatly  increased 
under  circumstances  so  favorable  to  their  disintegration.  In  the 
case  of  young  subjects,  especially,  where  the  teeth  are  but  imper- 
fectly consolidated,  and  in  adults  whose  teeth  are  defectively 
organized,  presenting  but  a  feeble  resistance  to  the  disintegrating 
agents  usually  present  in  the  mouth,  the  use  of  the  file,  for  the 
purpose  indicated,  is  pernicious,  and  should  never  be  resorted  to. 
When  it  is  found  necessary  to  separate  or  straighten  up  the  sides 
of  the  teeth  for  the  reception  of  clasps,  a  thin  diamond  disc  should 
be  employed,  as  it  is  less  annoying  to  the  patient,  does  the  work 


PARTIAL   DENTURES   RETAINED   BY    CLASPS. 


183 


in  iess  time,  and  is  not  so  destructive  to  the  tooth  structure  as 
the  file. 

Whenever  a  plain  necessity  for  this  operation  exists,  a  careful 
examination  of  all  the  teeth  to  which  it  is  proper  to  apply  clasps 
should  be  made,  and  if  decay  is  found  upon  their  proximate  sur- 
faces, the  separation  should  be  made  between  the  teeth  so  af- 
fected ;  and  this  circumstance  should,  in  most  cases,  determine 
the  selection,  though  the  affected  tooth  or  the  one  adjoining  may 
not  be  esteemed,  in  other  respects,  the  best  for  the  purposes  of 
support.  If  decay  exists  on  the  proximate  surface  of  only  one  of 
the  teeth  to  be  separated,  a  safe-sided  diamond  disc,  revolved  by 
the  dental  engine,  should  be  employed,  and  the  cutting  confined 
entirely  to  the  carious  tooth,  leaving  the  enamel  of  the  one  adjoin- 

Fig.  77. 


ing  unbroken.     The  cavity  of  decay  should  be  well  filled,  and  the 
filed  surface  thoroughly  condensed  and  polished. 

Modifications  in  the  Form  of  Clasps. — 1.  Plain  Band.  The 
most  usual  form  of  clasp  is  that  shown  in  Fig.  Jj.  It  consists  of 
a  plain  metallic  band  of  greater  or  less  width  and  thickness,  and 
is  made  to  embrace  the  larger  portion  of  the  circumference  of  the 
tooth.  In  regard  to  the  general  properties  of  metallic  clasps,  it 
may  be  said  that  they  should  be,  as  nearly  as  practicable,  of  the 
same  quality  or  fineness  as  the  plate  or  base  to  which  they  are 
united ;  they  should  be  heavy  enough  to  impart  adequate  security 
to  the  attachment — usual  thickness,  22  of  the  gage  plate — and 
sufficiently  elastic  to  embrace  accurately  the  more  contracted 
parts  of  the  teeth  after  having  been  temporarily  forced  apart 
in  passing  over  the  enlarged  portions  of  the  crowns.  In  con- 
structing a  plain  band  or  clasp,  a  strip  of  sheet-lead  or  other 


1 84 


MECHANICAL    DENTISTRY. 


pliable  substance  may  first  be  fitted  accurately  to  the  plaster 
tooth,  making  it  of  the  required  width,  and  shaping  the  edge 
next  the  gum  in  conformity  with  the  irregularities  in  the  latter 
around  the  neck  of  the  tooth ;  the  exact  counterpart  of  the  pattern 
thus  obtained  is  then  cut  from  the  plate  to  be  used  in  the  forma- 
tion of  the  clasp.  The  strip  thus  obtained  is  then  bent  with 
round-nosed  or  grooved  pliers  (Fig.  78),  until  conformed  as  per- 
fectly as  possible  to  every  portion  of  the  surface  of  the  tooth  em- 
braced by  it.  This  coaptation  should  be  sufficiently  accurate  to 
exclude  perfectly  all  solid  substances  from  between  the  clasp  and 
the  tooth.  A  more  accurate  adaptation  of  the  clasp  may  be  se- 
cured in  the  following  manner:  First  secure  a  pattern,  as  before 
described,  and  by  this  cut  from  a  thin  strip  of  platinum,  say  No. 

Fig.  78. 


30  or  32  of  the  gage  plate,  a  band  of  the  required  size  and  form, 
and  press  or  burnish  it  accurately  to  the  form  of  the  plaster  tooth. 
The  soft  and  pliant  condition  of  this  metal  will  admit  of  its  being 
easily  adapted  to  any  irregularities  upon  the  lateral  walls  of  the 
tooth.  The  band  thus  molded  to  the  tooth  is  then  carefully  re- 
moved from  the  model,  and  its  central  portion  filled  with  a  mix- 
ture of  plaster  and  sand,  with  a  small  metallic  wire  or  bar  passing 
through  the  center  to  support  it  while  soldering.  The  outer  or 
exposed  surface  is  then  coated  with  a  mixture  of  borax,  and  small 
scraps  or  fragments  of  gold  plate  of  equal  fineness  with  the  main 
plate  are  placed  at  intervals  and  fused  with  the  blowpipe  until 
diffused  uniformly  over  the  surface.  Small  pieces  may  be  added 
from  time  to  time,  until  the  required  thickness  of  the  clasp  is  ob- 
tained. The  piece  should  be  heated  uniformly  throughout  to  in- 
duce an  even  flow  of  the  gold  over  the  exterior  surface  of  the 


PARTIAL    DENTURES    RETAINED    BY    CLASPS.  1 85 

platinum  ring.  By  this  method  a  faultless  adaptation  of  the  clasp 
to  the  tooth  may  be  secured,  provided  the  form  of  the  latter  is 
correctly  represented  on  the  model.  In  all  cases  where  the  plain 
band  is  used,  it  should  be  made  as  broad  as  the  tooth  will  admit 
of,  as  a  clasp  so  formed  gives  greater  stability  to  the  plate,  and 
does  not  endanger  the  tooth  clasped  in  as  great  a  degree  as  a 
narrow  one. 

2.  Standard  Clasp. — To  guard  more  perfectly  against  the  reten- 
tion of  vitiated  secretions  and  particles  of  food  around  the  neck 
of  the  tooth,  a  method  of  constructing  clasps  has  been  devised 
and  introduced  to  the  notice  of  the  profession  by  Dr.  C.  W.  Spald- 
ing, which,  by  leaving  the  cervical  portion  of  the  tooth  in  a  great 
degree  uncovered,  permits,  as  he  claims,  the  action  of  the  tongue 

Fig.  79. 


and  the  natural  circulation  of  the  fluids  of  the  mouth,  to  wash  or 
cleanse  that  portion  of  the  tooth  most  liable  to  be  injuriously 
affected.  In  commenting  on  this  method,  Dr.  Spalding  remarks : 
"  I  have  for  many  years  been  in  the  habit  of  employing  narrow 
clasps  for  the  purposes  of  support,  making  them  of  sufficient 
thickness  to  give  the  required  strength,  and  attaching  them  to  the 
plate  by  means  of  standards,  so  arranged  as  to  induce  the  re- 
moval of  accumulations  between  the  clasp  and  tooth,  by  the  cir- 
culation of  the  saliva  (Fig.  79).  The  use  of  one  or  more  stand- 
ards as  a  means  of  attachment  also  provides,  by  a  variation  of 
their  length,  for  the  grasping  of  the  tooth  at  any  desired  point. 
If  the  tooth  is  long,  and  particularly  if  it  is  at  the  same  time  bell- 
crowned,  the  point  selected  should  be  toward  the  grinding  sur- 


1 86  MECHANICAL   DENTISTRY. 

face,  as  far  from  the  gum  as  is  found  practicable.  If  the  tooth  is 
short  and  of  such  form  that  it  can  be  successfully  clasped  at  no 
other  point  than  that  near  the  gum,  the  plate  should  be  cut  away 
at  least  I  or  1^2  lines  from  the  tooth,  and  standards  introduced 
for  the  purpose  of  promoting  circulation,  by  affording  a  free  pass- 
age for  the  ingress  and  egress  of  fluids.  These  standards  should 
also  be  narrow,  no  wider  than  the  clasp  itself,  and  should  consti- 
tute the  only  point  of  union  between  the  clasp  and  plate.  Half- 
round  wire  will  be  found  to  be  a  very  convenient  article  for  mak- 
ing clasps.  The  particular  form  of  the  clasp  is,  however,  imma- 
terial if  it  is  both  narrow  and  strong." 

3.  Scalloped  Clasp. — Somewhat  analogous  in  form  to  the  clasp 
just  described,  and  constructed  with  a  similar  design,  is  the  one 
recommended  by  Dr.  B.  T.  Whitney.  A  plain  band  of  gold  is 
fitted  to  the  tooth  in  the  manner  first  described,  when  that  por- 
tion of  it  next  the  gum  on  the  lingual  side  of  the  tooth  is  scal- 
loped or  cut  away  in  the  form  of  a  semicircle  or  arch,  the  ends  of 
the  clasp  being  in  like  manner  narrowed  sufficiently  to  relieve 
them  from  contact  with  the  neck  of  the  tooth.  The  intermediate 
points  of  the  clasp  which  serve  to  unite  the  latter  to  the  base  may 
be  two  or  more  in  number,  and  should  be  wide  enough  to  impart 
adequate  strength  to  the  attachment.  A  clasp  so  formed  and  ap- 
plied to  the  base  will  present  very  nearly  the  appearance  of  the 
standard  clasp  as  represented  in  Fig.  79.  Dr.  W.  recommends 
soldering  but  a  single  point  at  first,  and  then  having  tried  the 
plate  in  the  mouth  and  adjusted  the  clasp  properly  to  the  tooth, 
remove  and  solder  the  remaining  point  or  points. 

4.  Partial  or  Stay  Clasp. — This  form  of  clasp,  instead  of  em- 
bracing the  tooth,  is  designed  to  steady  or  fix  the  substitute  in 
place,  by  simply  resting  against  one  side  of  the  tooth  to  which  it 
is  applied.  They  should  be  so  connected  to  the  plate  that,  when 
pressed  over  the  enlarged  portions  of  the  crowns  of  the  teeth,  they 
will  spring  readily  into  place  and  adapt  themselves  closely  to  the 
more  contracted  parts  near  the  gum.  In  cases  where  there  is  no 
adequate  opposing  force  to  that  exerted  by  the  clasp,  care  should 
be  taken  that  no  more  pressure  is  produced  than  is  necessary  to 
keep  the  substitute  in  place,  as,  without  this  precaution,  outward 
displacement  of  the  teeth  is  liable  to  occur,  and  the  appliance, 
losing  its  bearing  upon  the  teeth,  soon  becomes  loosened  and  in- 


PARTIAL    DENTURES    RETAINED    BY    CLASPS. 


I87 


secure  in  the  mouth.  The  result  alluded  to  should  be  particu- 
larly guarded  against  in  the  case  of  young  subjects,  whose  teeth 
are  easily  moved  by  the  application  of  very  slight  forces. 

Modifications  in  the  Form  of  Plates  for  Partial  Dentures  Sup- 
ported in  the  Mouth  by  Clasps. — The  particular  form  and  dimen- 
sions of  a  plate,  when  clasps  are  used,  will  be  mainly  determined 
by  the  number  and  position  of  the  teeth  to  be  replaced,  and  by  the 
location  of  the  natural  organs  to  which  the  clasps  are  attached. 
It  will  be  sufficient  in  this  place  to  indicate  the  leading  forms  as 
they  relate  to  the  substitution  of  the  several  classes  of  teeth.     In 


Fig.  80. 


supplying  the  loss  of  a  superior  central  or  lateral  incisor,  it  will 
be  sufficient  in  many  cases  to  attach  the  plate  to  either  a  bicuspid 
or  molar  on  the  same  side.  If  two  or  more  of  the  front  teeth, 
however,  are  to  be  replaced,  it  is  better  to  extend  the  plate  on 
each  side  of  the  palatal  arch,  and  attach  to  a  bicuspid  or  molar 
(Fig.  80).  In  all  cases  where  it  is  necessary  to  extend  a  narrow 
plate  from  the  extreme  front  part  of  the  mouth  to  a  single  tooth 
situated  posteriorly  in  the  arch,  the  former  should  be  strength- 
ened by  soldering  a  narrow  rim  of  plate  or  half-round  wire  along 
the  border  next  the  teeth,  and  the  clasp  should,  whenever  prac- 
ticable, pass  in  front  of  and  embrace  the  anterior  face  of  the  tooth 
to  which  it  is  applied. 

If  an  anterior  bicuspid   is  to  be  replaced,   the   plate   may  be 
attached  to  the  adjoining  bicuspid,  or  if  both  are  absent,  then  to 


I5C  MECHANICAL    DENTISTRY. 

the  first  molar,  or  the  clasp  may  embrace  both  of  the  latter  if 
remaining  and  no  separation  between  them  exists. 

Take  a  case  where  it  is  necessary  to  supply  the  loss  of  the  two 
bicuspids  on  one  side,  and  the  first  bicuspid  and  first  molar  on  the 
opposite,  the  plate  being-  attached  to  an  anterior  molar  and  second 
bicuspid.  The  antero-posterior  extension  of  the  plate,  in  con- 
nection with  the  bicuspid  tooth,  greatly  favors  the  stability  of  the 
substitute,  and,  provided  the  plate  and  clasp  are  accurately  fitted 
to  the  parts,  the  support  afforded  by  a  bicuspid  tooth  under  such 
circumstances  is  equivalent  to  that  furnished  by  a  clasp  about  a 

Fig.  8i. 


firm  and  well-formed  molar.     A  base  so  supported  may  be  made 
to  sustain  a  number  of  teeth  with  much  security. 

Either  the  anterior  or  posterior  molars,  if  firm  and  securely 
attached  in  the  jaw,  will  afford  adequate  support  to  a  plate  replac- 
ing all  of  the  teeth  anterior  to  them.  Even  a  single  molar  situ- 
ated on  either  side  of  the  arch,  if  similarly  circumstanced,  may  be 
made  to  sustain,  with  tolerable  firmness,  a  base  supplying  the  loss 
of  all  the  remaining  teeth,  though,  ordinarily,  it  is  better  to  extract 
such  teeth  and  substitute  an  entire  upper  denture.  Tn  all  cases 
where  any  considerable  number  of  teeth  anterior  to  those  clasped 
are  to  be  replaced,  and  a  vacuity  on  the  ridge  exists  posterior  to 
the  latter,  the  plate  should  be  extended  back  and  overlap  the  ridge 
(Fig.  8ij,  the  latter  affording  a  counterpoint  of  resistance  when 
traction  is  made  upon  the  anterior  teeth,  thus  directing  the  forces 


PARTIAL    DENTURES    RETAINED    BY    CLASPS. 


189 


applied  more  on  a  line  with  the  long  axes  of  the  teeth  that  sustain 
the  appliance. 

In  supplying  the  loss  of  the  inferior  molars  and  bicuspids,  or 
any  number  of  these  teeth,  the  form  of  plate  represented  in  Fig. 
82  is  generally  employed.  The  parts  of  the  plate  overlapping  and 
resting  upon  the  ridge  behind  are  connected  with  each  other  by 
a  narrow  strip  of  plate  extending  round  the  ridge,  hugging  the 
lingual  side  of  the  anterior  teeth.  This  latter  portion  of  the  plate 
should  be  accurately  swaged  to  the  form  of  the  gum  on  which  it 
rests,  and  should  be  made  narrow  enough  to  avoid  encroaching 
upon  the  reflected  portion  of  mucous  membrane,  the  glands  be- 
neath the  tongue,  or  the 
frenum  linguae.  Fig.  82. 

Reinforcing.  —  To  avoid 
wounding  these  parts,  and 
to  allow  them  unobstructed 
play,  it  will  be  necessary  to 
make  this  portion  of  the 
plate  quite  narrow;  and  as 
a  single  thickness  of  plate 
would  not  impart  adequate 
strength,  it  is  better  practice 
to  reinforce  or  double  this 
connecting  band — the  dupli- 
cate band  extending  back  to 

the  lateral  wings  of  the  plate,  and  crossing  them  obliquely,  as  in- 
dicated by  the  lines  in  Fig.  82.  Additional  strength  will  be  given 
by  doubling  the  entire  plate,  but  this  is  not  generally  required. 
The  outer  border  of  those  portions  of  the  plate  overlapping  the 
ridge  may  be  turned  up  to  the  depth  of  from  y2  of  a  line  to  a  line, 
to  form  a  groove  or  socket  for  the  reception  of  the  ends  of  gum 
teeth,  or  blocks,  if  such  are  used ;  while  the  inner  margins  should 
terminate  in  a  rounded  edge,  extending  from  heel  to  heel  of  the 
plate,  this  form  being  given  to  it  either  by  turning  the  edge  over 
and  filling  in  the  groove  with  solder,  or  by  soldering  a  narrow 
strip  of  plate  or  half-round  gold  wire  along  the  border.  The  cir- 
cumstances or  conditions  which  make  the  use  of  clasps  necessary 
in  these  cases,  as  well  as  those,  also,  which  contraindicate  their 
employment,  have  already  been  noticed.     The  practice  of  extend- 


190 


MECHANICAL    DENTISTRY. 


ing  a  narrow  band  or  wire  from  the  sides  of  the  plate  round  the 
outer  border  of  the  ridge  in  front  of  the  anterior  teeth,  to  prevent 
a  backward  displacement  of  the  base,  is  liable  to  produce  irrita- 
tion and  tenderness  of  the  mucous  membrane  immediately  over 
the  roots  of  the  anterior  teeth,  and  should,  therefore,  never  be 
resorted  to  unless  there  are  no  teeth  remaining  to  which  clasps 
may  be  applied. 

If  the  appliance  is  designed  to  restore  the  loss  of  teeth  recently 
extracted,  and  where  but  little  or  no  change  has  occurred  from 
absorption  of  the  parts,  the  portions  of  the  plate  which  pass  in 
between  the  adjoining  teeth  should  terminate  a  line  or  more 
within  the  outer  circle  of  the  remaining  teeth ;  and  where  the 
space,  if  it  happens  in  the  front  part  of  the  mouth,  admits  of  two 
or  more  teeth,  the  edges  of  the  extended  portion  of  plate  should 
be  scalloped  in  correspondence  with  the  festoons  of  the  gum,  as 
seen  in  Fig.  80.  In  such  cases,  plain  or  plate  teeth,  by  which  is 
meant  those  which  represent  only  the  crowns  of  the  natural  or- 
gans, should  be  employed;  these,  resting  on  the  edge  of  the  plate, 
will  overlap  somewhat,  with  their  anterior  edges  resting  directly 
upon  the  gum  in  front,  taking  the  place  occupied  by  the  crowns 
of  the  extracted  teeth.  On  the  other  hand,  if  sufficient  time  has 
elapsed  after  the  extraction  of  the  teeth  to  permit  the  changes  in 
the  form  of  the  ridge  to  occur  incident  to  partial  or  complete 
absorption  of  the  parts,  and  a  greater  or  less  concavity  exists 
between  and  above  the  teeth  on  the  outside  of  the  jaw,  the  plate, 
where  it  passes  into  the  interspace,  should  extend  some  distance 
over  the  border  of  the  ridge. 

Swaging  the  Plate. — Having  determined  upon  the  proper  form 
and  dimensions  of  the  plate  for  any  given  case,  its  outlines  may 
first  be  traced  upon  the  model ;  from  this  an  exact  pattern  in  lead 
may  be  obtained,  or  the  pattern  may  be  sufficiently  ample  to  par- 
tially overlap  the  cut  extremities  of  the  teeth  when  the  latter  are 
not  represented  upon  the  die,  having  been  previously  cut  from 
the  model,  as  shown  in  Fig.  57,  page  150.  The  outlines  of  the 
pattern  arc  then  traced  upon  the  plate  of  gold,  or  other  metal 
used  for  the  base.  The  redundant  portions  of  plate  are  then  cut 
away  with  plate-shears  and  forceps,  and  the  edges  trimmed 
smooth  with  a  file.  A  very  convenient  and  almost  indispensable 
instrument  for  cutting  away  the  plate  in   conformity  with  the 


PARTIAL    DENTURES    RETAINED    BY    CLASPS. 


191 


Fig.  83. 


palatal  curvatures  of  the  teeth,  is  the  plate-forceps  as  exhibited 
in  Fig.  83. 

The  plate  cut  to  the  proper  form  is  now  placed  upon  the  die  and 
brought  as  nearly  as  possible  into  adaptation  with  a  wooden  or 
horn  mallet ;  it  is  then  placed  between  the  die  and  counter,  the 
latter  resting  on  an  anvil  or  other  equally  resisting  surface,  when 
the  two  metallic  pieces  are  brought  forcibly  together  with  a  few 
steady  and  well-directed  blows  of  a  heavy  hammer.  Tilting  of 
the  die,  resulting  sometimes  unavoidably  from  a  one-sided  blow, 
may  be  obviated  by  placing  a  cone-shaped  piece  of  cast-iron, 
brass,  or  zinc  over  the  die,  the  base  of  the  cone  resting  on  the 
back  of  the  die ;  by  this  expedient  the  force  of  the  blow  is  equal- 
ized and  concentrated  more  directly  over  the  die.  The  metallic 
swages  should  at  first  be  brought  cau- 
tiously together,  and  should  be  separated 
after  the  first  blow  or  two,  to  enable  the 
manipulator  to  detect  and  remedy  any 
malposition  of  the  plate  before  it  becomes 
intractable  from  continued  swaging.  If, 
in  the  process  of  stamping,  any  portion 
of  the  plate  is  found  cracking  or  parting, 
its  further  extension  at  that  point  may  be 
prevented  by  flowing  a  little  solder  at  the 
termination  of  the  fissure. 

Annealing  the  Plate. — During  the  pro- 
gress of  swaging  the  plate  should  be  fre- 
quently annealed,  which  is  done  by  bring- 
ing it  to  a  full  red  heat  under  the  blow- 
pipe or  by  placing  it  in  the  furnace ;  the 
plate  is  thus  rendered  more  pliant,  and 
can  be  more  readily  and  perfectly  forced  into  adaptation  to  the 
irregularities  on  the  face  of  the  die. 

If,  after  somewhat  protracted  swaging,  the  plate  is  not  con- 
formed perfectly  to  the  face  of  the  die,  another  and  unused  coun- 
ter should  be  substituted  for  that  in  use ;  and,  indeed,  it  is  better 
in  all  cases  to  have  duplicate  copies  both  of  the  die  and  counter  in 
reserve  with  which  to  complete  the  swaging,  inasmuch  as  more 
or  less  deformity  of  both  swages  unavoidably  occurs  before  the 
plate  is  brought  into  very  accurate  coaptation  with  the  die.     The 


I92  MECHANICAL   DENTISTRY. 

stamping  conducted  thus  far,  the  plate  may  be  applied  to  the  plas- 
ter model,  and  if  found  too  full  at  any  point,  it  should  be  trimmed 
with  a  file  to  the  exact  dimensions  required.  The  margins  of  the 
plate  adjoining  the  necks  of  the  teeth  should  be  permitted  either 
to  lie  closely  to  them,  or  should  be  cut  away,  leaving  a  space 
equal  to  a  line  or  more  between  the  plate  and  the  teeth;  for  if 
but  a  very  narrow  line  of  uncovered  gum  remains  at  these  points, 
injury  to  the  parts  immediately  surrounding  the  necks  of  the 
teeth  is  more  liable  to  occur  from  strangulation  of  the  interposed 
gum,  than  if  the  plate  were  further  removed  from  the  teeth  or 
rested  directly  against  them. 

Adjusting  and  Strengthening  the  Projections  or  Tongues  of 
the  Plate. — If  the  portion  of  the  plate  which  passes  in  between 
the  remaining  teeth  is  quite  narrow,  as  where  but  a  single  tooth 
is  to  be  supplied,  it  should  be  strengthened  by  wiring  the  edges  or 
doubling  the  plate  at  such  a  point.  It  is  also  advisable  in  many 
cases,  in  order  to  provide  more  perfectly  against  fracture  or  dis- 
tortion of  the  base  in  mastication,  to  wire  or  double  the  entire 
border  of  the  plate  adjoining  the  necks  of  the  teeth.  Narrow 
bands  of  gold  resting  against  the  necks  of  the  teeth,  constructed 
and  adjusted  after  the  manner  of  stay  clasps,  are  sometimes  sol- 
dered to  the  edge  of  the  plate  next  the  teeth ;  but  unless  the  sub- 
stitute is  frequently  cleansed,  as  well,  also,  as  the  teeth  to  which 
the  clasps  are  applied,  serious  injury  is  likely  to  be  inflicted  upon 
the  teeth  implicated. 

The  edges  of  those  parts  of  the  plate  occupying  the  vacuities 
on  the  ridge  should  be  filed  thin  to  admit  of  a  more  accurate  adap- 
tation of  the  artificial  with  the  natural  gum,  and  should  not,  as 
before  observed,  ordinarily  extend  beyond  the  outer  circle  of  the 
contiguous  teeth,  allowing  the  gum  extremity  of  the  artificial  tooth 
to  overlap  and  rest  directly  on  the  natural  gum  above.  If,  how- 
ever, the  concavity  between  and  above  the  teeth  on  the  external 
border  of  the  ridge  is  considerable,  the  interdentinal  portions  of 
the  plate  should  overlap  the  border  completely  and  underlie  the 
porcelain  gum. 

Adjusting  Clasps  to  the  Plate. — Having  proceeded  thus  far  in 
the  operation,  the  plate  and  clasps  should  next  be  united  to  each 
other,  and  the  utility  and  comfort  of  the  appliance  in  the  mouth,  as 
well  as  the  safety  of  the  natural  organs  used  for  the  purpose  of  sup- 


PARTIAL   DENTURES   RETAINED   BY    CLASPS. 


193 


port,  will  depend  in  a  great  measure  upon  the  accurateness  of  the 
relation  of  the  several  parts  of  the  appliance  to  the  organs  of  the 
mouth;  it  being  a  matter  of  primary  importance  that  the  various 
parts  of  the  substitute  should  be  so  adjusted  to  the  remaining 
teeth — especially  those  to  which  the  clasps  are  applied — and  the 
ridge  and  palate,  that  it  shall  not,  in  any  material  degree,  act  as  a 
retractor  upon  the  organs  of  support,  or  furnish  interspaces  for 
the  lodgment  of  food,  while  at  the  same  time  it  should  be  so 
fitted  as  easily  to  be  removed  and  readjusted  by  the  patient. 

Manner  of  Securing  Clasps  to  the  Plate. — The  clasps  having 
been  fitted  to  the  plaster  teeth  and  the  base  swaged  to  the  form  of 
the  palatal  arch  and  ridge,  the  plate  is  placed  in  its  proper  position 
in  the  mouth  and  an  impression  in  wax  taken  of  the. latter  with 
the  plate  in  place.  The  impression,  with  the  plate  adhering,  is 
then  removed  from  the  mouth,  its  surface  oiled,  and  a  model 
obtained  in  the  manner  heretofore  described.  If,  in  separating 
the  model  and  impression,  the  plate  adheres  to  the  latter,  it  should 
be  detached  and  adjusted  to  the  model  and  the  clasps  arranged 
upon  the  plaster  teeth.  The  plate  and  clasps  may  now  be  at- 
tached to  each  other  temporarily,  with  adhesive  wax,  in  the  rela- 
tion they  occupy  on  the  model,  and  then  removed  carefully  and 
the  clasps  and  palatal  face  of  the  plate  imbedded  in  a  mixture  of 
nearly  equal  parts  of  plaster,  sand,  and  asbestos.  Before  uniting 
the  two  pieces  on  the  model  with  wax,  however,  the  ends  of  the 
clasps  should  be  slightly  spread  apart,  in  order  that  they  may 
part  readily  from  the  plaster  teeth,  without,  in  any  degree,  chang- 
ing their  exact  relation  to  the  plate ;  in  doing  this,  it  should  be 
observed  that  all  parts  of  the  clasps  which  are  to  be  united  to 
the  plate  should  remain  in  close  contact  with  the  plaster  teeth. 
After  the  plaster  mixture,  in  which  the  plate  and  clasps  are  im- 
bedded, has  become  sufficiently  hard,  the  portions  of  wax  which 
temporarily  united  the  latter  should  be  removed,  and  the  surfaces 
of  the  clasps  and  plate,  where  they  unite  with  each  other,  coated 
with  borax  ground  in  water  to  the  consistency  of  cream ;  small 
pieces  of  solder  are  then  placed  along  the  lines  of  contact,  the  in- 
vestment heated  in  the  furnace  until  the  plate  acquires  a  dull  red 
heat,  when  it  is  removed,  placed  upon  a  suitable  holder,  and  the 
solder  fused  with  the  blowpipe. 

Whenever  the  form  and  inclination  of  the  teeth  to  be  clasped 

13 


194 


MECHANICAL   DENTISTRY. 


are  not  fairly  represented  on  the  model,  owing  to  dragging  or  dis- 
placement of  the  wax  in  withdrawing  the  impression,  the  difficul- 
ties of  securing  a  proper  relative  adjustment  of  the  several  parts 
of  the  appliance  will  be  increased ;  but  either  of  the  following 
methods,  if  carefully  and  accurately  manipulated,  will  secure 
accurate  results : 

i.  Plaster-of-Paris  or  modeling  compound  may  be  substituted 
for  wax  when  taking  an  impression  with  the  plate  in  the  mouth. 
With  the  proper  use  of  these  materials,  the  exact  form  and  in- 
clination of  the  teeth  will  be  better  preserved ;  and  when  em- 
ployed they  should  be  filled  in  with  plaster  for  the  model  imme- 
diately after  removing  them  from  the  mouth.  The  subsequent 
steps  in  the  operation  are  precisely  similar  to  those  described 
when  wax  is  used. 

2.  Another  method  is  to  adjust  the  clasps  and  plate  to  the  parts 
in  the  mouth,  attach  them  temporarily  in  their  proper  relation, 
and  remove,  invest,  and  solder  in  the  usual  way.  This  may  be 
accomplished  in  the  following  manner:  First,  spread  apart  the 
ends  of  the  clasp  somewhat  to  permit  it  easily  to  be  removed  from 
the  tooth ;  place  this  upon  the  tooth  in  the  mouth  to  be  clasped ; 
then  adjust  the  plate,  and  attach  the  two  to  each  other  by  press- 
ing a  piece  of  stiff,  adhesive  wax  in  against  the  clasp  and  plate 
where  they  unite ;  harden  the  wax  by  placing  against  it,  for  a  few 
minutes,  a  pledget  of  cotton,  or  the  end  of  a  napkin,  moist  with 
cold  water;  then  remove  the  plate  and  clasp  carefully  from  the 
mouth,  and  invest  and  solder  as  before.  The  plate,  with  one  clasp 
permanently  attached,  is  now  placed  back  in  the  mouth,  and  the 
second  clasp  adjusted  to  the  tooth  on  the  opposite  side  in  the 
manner  before  alluded  to ;  this  is  then  temporarily  fastened  to  the 
plate  and  otherwise  treated  in  like  manner  as  the  one  first  de- 
scribed. If  the  teeth  to  be  clasped  are  favorably  formed  and 
regularly  arranged  in  the  arch,  both  clasps  may,  at  the  same  time, 
be  temporarily  attached  to  the  plate  in  the  first  instance;  if  not, 
it  will  be  impracticable  to  remove  them  from  the  teeth  without 
disturbing  the  wax  and  changing  their  relation  to  the  base  and 
the  teeth  clasped.  The  additional  labor  and  consumption  of  time 
incident  to  a  separate  attachment  of  the  clasps  will,  in  proportion 
as  they  secure  better  results,  amply  reward  the  operator  for  his 
painstaking. 


PARTIAL   DENTURES    RETAINED    BY    CLASPS. 


195 


Plaster  is  sometimes  substituted  for  wax  in  this  process ;  in 
which  case  it  is  introduced  into  the  mouth  on  a  small  piece  of  wax 
or  sheet-lead  and  pressed  gently  against  the  uniting  portions  of 
the  plate  and  clasp,  and  allowed  to  remain  until  sufficiently  hard. 
Any  superfluous  portions  around  the  tooth  that  may  hinder  the 
easy  removal  of  the  clasp  should  now  be  cut  away,  when  the 
pieces  so  attached  to  each  other  are  removed  from  the  mouth.  A 
separation  of  the  plaster  from  the  clasp  or  plate,  or  both,  may  oc- 
cur when  removing  the  latter ;  in  this  case  the  several  parts  may 
be  readily  and  accurately  adjusted  to  each  other  again  in  their 
exact  relation  when  out  of  the  mouth,  as  the  latter  will  be  plainly 
indicated  by  the  impression  made  by  the  plate  and  clasp  in  the 
plaster.  Being  readjusted,  they  may  be  further  secured  by  stick- 
ing them  together  with  a  little  softened  wax,  when  they  are  in- 
vested, the  temporary  fastening  of  plaster  removed,  and  the  pieces 
united  by  soldering.  The  use  of  plaster  in  these  cases  unques- 
tionably possesses  many  advantages  over  wax  for  the  purpose, 
as  the  latter  is  liable,  unless  most  skilfully  manipulated,  to  become 

Fig.  84. 


displaced  in  removing  it  from  the  mouth ;  and  this  change,  when 
it  occurs,  not  being  indicated  by  inspection  of  the  wax,  is  incapa- 
ble of  timely  correction. 

3.  Still  another  method  is  that  contrived  by  Dr.  Fogle  and 
described  by  Dr.  Cushman  in  the  tenth  volume  of  the  American 
Journal  of  Dental  Science.  It  consists  in  securing  the  proper  rela- 
tion of  the  clasps  to  the  teeth  in  the  mouth  by  the  use,  in  the  first 
instance,  of  what  are  termed  "  temporary  fastenings."     The  plate 


iq6  mechanical  dentistry. 

and  clasps  are  first  applied  to  the  model,  and  are  then  connected 
by  a  narrow  strip  of  plate  or  piece  of  wire  bent  in  the  form  of  a 
bow,  the  concavity  facing  the  model,  one  end  of  which  is  soldered 
to  the  palatal  side  of  the  clasp,  and  the  other  to  a  contiguous 
point  upon  the  plate,  as  exhibited  in  Fig.  84,  and  the  pieces  thus 
temporarily  united  are  removed  from  the  model  and  adjusted  to 
the  parts  in  the  mouth.  If  the  position  of  the  clasps  is  found  in 
any  respect  faulty,  they  can  be  easily  and  accurately  adapted  to 
the  walls  of  the  teeth  by  bending  or  twisting  the  connecting  strip 
in  any  desired  direction  with  pliers  or  other  instruments  suitable 
for  the  purpose.  This  accomplished,  the  plate  and  clasps  are 
removed,  and  the  operation  of  permanently  uniting  the  clasps  to 
the  plate  performed  in  the  usual  manner. 

In  the  use  of  partial  dentures,  there  is  always  increased  liability 
to  injury  of  the  soft  parts  by  reason  of  pressure  being  concen- 
trated upon  limited  or  circumscribed  portions  of  the  alveolar  ridge 
embraced  in  interdental  spaces,  thereby  diminishing  resistance  to 
the  pressure  of  the  plate  at  such  points.  As  a  consequence,  the 
latter  is  forced  into  the  soft  tissues,  producing  more  or  less  irrita- 
tion and  inflammation,  and  consequent  tenderness  and  pain  on 
pressure,  and,  generally,  either  partial  denudation  of  the  necks  of 
the  natural  teeth  abutting  upon  the  interdental  spaces,  or  stran- 
gulation, congestion,  and  hypertrophy  of  the  gum  in  immediate 
contact  with  them. 

Clasps  with  Spurs. — A  simple  device,  by  which  the  results 
alluded  to  may  be  obviated,  consists  in  attaching  to  the  clasps, 
above  or  below,  a  strip  or  spur  of  gold  at  suitable  points,  long 
enough  to  overlap  or  rest  upon  the  masticating  surface  of  the 
tooth  clasped,  forming  a  hook  or  partial  crown-cap.  These  will 
afford  fixed  points  of  resistance  to  pressure  and  effectually  pre- 
vent the  plate  impinging  upon  the  underlying  tissues.  The  same 
expedient  may  be  adopted  also  in  the  case  of  partial  dentures 
retained  by  adhesion  or  atmospheric  pressure,  by  attaching  sim- 
ilar gold  spurs  or  caps  to  the  border  of  the  plate  at  suitable  points 
contiguous  to  the  bicuspids  and  molars. 

Charles  Rathbun,  of  London,  England,  relates,  in  the  Dental 
Cosmos  of  December,  1886,  a  method  of  constructing  partial 
pieces  which  embodies  the  same  principle  of  crown-support  as 
described  above,  the  essential  details  of  which  are  here  given: 


PARTIAL   DENTURES    RETAINED    BY    CLASPS. 


197 


In  Fig.  85  we  have  the  first  bicuspid  standing;  the  second  bi- 
cuspid and  cuspid  in  that  case  filling  the  role  of  the  lateral,  miss- 
ing from  its  position.  The  bicuspid  is  pear-shaped,  its  largest 
diameter  being  just  below  the  grinding  surface,  and  the  molar  is 
a  trifle  undercut.  A  No.  7  or  8  English  gage  gold  plate,  struck 
from  a  model  made  from  a  modeling  compound  impression,  would 
not  touch  the  necks  of  either  the  bicuspid  or  molar,  owing  to  the 
fact  that  these  teeth  would  "  draw  "  a  little  in  the  impression,  and 
it  should  be  fitted  over  the  shoulder  at  the  neck  on  the  lingual  side 
of  the  cuspid,  left  clear  of  it  at  the  distal  side,  and  have  a  stay  or 
clip  resting  just  above  the  prominence  on  that  side  of  the  tooth. 
A  band  should  be  soldered  to  the  plate  at  the  lingual  side  of  the 
bicuspid,  to  grasp  that  tooth  at  its  largest  point,  viz.,  about  one- 
third  of  the  distance  from  the  grinding  surface  to  the  neck ;  also, 
a  band  fitted  to  the  molar  to  reach  from  about  the  middle  of  the 
lingual  side  far  enough  around  the  mesial  face  to  clasp  over  the 
prominence  at  the  mesio-buccal  aspect  of  the  tooth ;  this  band  to 


Fig.  85. 


Fig.  86. 


be  fitted  to  grasp  the  tooth  at  its  fullest  part,  as  in  the  case  of 
the  bicuspid.  (See  Fig.  86.)  Wires  or  clasps  at  the  necks  of 
teeth  of  this  class  do  no  end  of  damage  to  the  teeth,  and  are  open 
to  the  great  objection  that  a  case  may  go  in  very  hard,  and  yet 
when  the  clasps  are  past  the  large  part  of  the  teeth  the  case  is 
quite  loose  and  shaky.  The  bands  I  have  described  do  not  bear 
on  the  teeth  at  all  until  the  case  is  within  about  a  line  of  its  place, 
and  then  each  one  bears  on  its  own  tooth  irrespective  of  the 
others,  and,  be  it  borne  in  mind,  touches  the  tooth  at  a  point 
where  the  chance  of  decay  is  simply  infinitesimal.  If  a  porce- 
lain cuspid  and  bicuspid  be  ground  in  properly,  the  clasps  will 
not  be  visible  externally,  which  cannot  be  said  of  the  broad  gold 
band  carried  across  the  buccal  face  of  the  natural  tooth. 


CHAPTER  XVII. 

PARTIAL   DENTURES   SUPPORTED   BY  ATMOSPHERIC   PRESSURE 

OR  ADHESION. 

The  method  of  attaching  partial  sets  of  teeth  to  the  superior 
jaw  by  means  of  atmospheric  pressure,  or  by  adhesion,  is  much 
more  generally  practised  than  formerly,  and  whenever  the  con- 
dition of  the  soft  parts  of  the  mouth,  the  general  configuration  of 
the  palatal  arch,  and  the  antagonism  or  occlusion  of  the  artificial 
with  the  natural  teeth  favor  its  adoption,  there  are  good  and  suffi- 
cient reasons  why  either  of  these  forces  should,  in  all  practicable 
cases,  be  utilized  in  preference  to  the  use  of  clasps  for  purposes  of 
attachment. 

Modifications  in  the  Form  of  the  Base. — If  vacuities  exist  at 
various  points  on  the  ridge,  the  plate  on  which  the  teeth  of 
replacement  are  mounted  should  be  ample  in  its  dimensions, 
covering  nearly  or  quite  all  of  the  hard  palate.  The  general  form 
of  the  base,  where  several  teeth  scattered  throughout  the  arch  are 
required,  is  shown  in  Fig.  87.  In  most  cases,  whether  but  one  or 
a  greater  number  of  teeth  are  to  be  replaced,  increased  adherence 
and  stability  of  the  substitute  will  be  better  secured  by  permitting 
the  plate  to  cover  the  larger  portion  of  the  roof  of  the  mouth ; 
though,  in  cases  that  present  the  best  form  of  the  vault,  a  dimin- 
ished surface  may  be  given  to  the  base  with  equally  satisfactory 
results.  In  the  substitution  of  a  single  incisor,  for  example,  it  will 
frequently  be  sufficient  to  employ  a  very  small  plate,  covering  only 
a  part  of  the  anterior  sloping  wall  of  the  palate.  In  the  latter  case 
the  plate  used  may  be  very  thin,  say  No.  30  standard  gage ;  it 
will  thus  impede  the  movements  of  the  tongue  less,  and  may  be 
swaged  more  accurately  to  the  parts.  If  constructed  with  an  air- 
chamber,  the  latter  should  be  quite  shallow. 

A  somewhat  anomalous  form  of  atmospheric-pressure  plate, 
employed  in  the  substitution  of  one  or  two  bicuspid  teeth  on  each 
side,  is  described  by  Professor  Taft,  the  design  of  which  is  to 
secure  in  such  cases  increased  stability  of  the  substitute,  while 

198 


PARTIAL   DENTURES    HELD    BY    ATMOSPHERIC    PRESSURE. 


199 


much  of  the  palatal  arch  is  left  uncovered.  It  consists  of  two  lat- 
eral cavity  plates  accurately  adjusted  to  the  sloping  walls  of  the 
palate  on  each  side,  immediately  adjoining  and  partly  occupying 
the  spaces  to  be  supplied.  These  lateral  plates  may  be  made  as 
large  as  a  dime,  or  somewhat  larger,  and  of  an  elliptical  shape  if 
both  bicuspids  on  the  same  side  are  to  be  replaced,  and  are  con- 
nected with  each  other  by  a  narrow  band  of  gold  plate,  two  lines 
or  more  in  width,  having  an  anterior  curvature,  and  resting  on  the 
front  wall  of  the  palate,  two  or  three  lines  behind  the  anterior 
teeth.  The  entire  appliance  may  be  constructed  from  a  single 
piece  of  gold  plate  swaged  accurately  to  the  parts ;  or  the  lateral 
plates  and  connecting  band  may  be  separately  swaged  and  secured 

Fig.  87. 


in  their  proper  relation  to  each  other  in  the  mouth  with  wax  or 
plaster,  when  they  are  carefully  removed,  invested,  and  soldered 
together ;  it  should  then  be  reswaged  to  correct  any  change  of  re- 
lation that  may  have  happened  during  the  concluding  manipula- 
tions. The  liability  of  the  plate  to  ride  upon  the  central  and  raised 
portion  of  the  palate,  when  pressure  is  made  upon  one  side,  throw- 
ing the  plate  off  from  the  ridge  on  the  other,  as  in  the  case  of  a 
base  extending  across  the  arch,  is  in  a  great  degree  obviated  by 
the  method  just  described. 

Manner  of  Forming  an  Air-chamber. — Atmospheric-pressure 
plates  for  partial  cases  are  constructed  with  a  central  air-cham- 
ber ;  in  which  case,  the  part  of  the  model  representing  the  chamber 


200  MECHANICAL   DENTISTRY. 

may  be  formed  in  either  of  the  ways  mentioned  in  the  chapter  on 
Plaster  Models.  The  model  prepared,  the  form  of  the  plate  to  be 
used  is  first  indicated  thereon,  and  from  this  a  pattern  in  sheet- 
lead  is  obtained,  which  is  placed  on  the  plate  of  gold  or  other 
metal,  and  its  outlines  traced  with  a  pointed  instrument ;  the  re- 
dundant portions  are  then  cut  away  with  plate  shears  and  forceps. 
The  plate  is  now  placed  on  the  die  and  brought  as  nearly  as  pos- 
sible into  adaptation  to  the  latter  with  the  No.  i  counter-die  (see 
Progressive  Counter-dies)  ;  it  is  then  interposed  between  the  die 
and  the  larger  counter,  and  swaged  until  it  conforms  perfectly  to 
the  face  of  the  former,  annealing  the  plate  frequently  to  render  it 
more  pliant  and  manageable  under  the  hammer. 

The  Use  of  a  Tracer  in  the  Swaging  Process. — Unless  the  plate 
used  is  purer  and  thinner  than  is  generally  employed,  or  than  is 
consistent  with  the  required  strength,  it  will  fail  to  be  forced  per- 
fectly into  the  groove  around  the  chamber  by  the  process  of  swag- 
ing alone ;  a  more  definite  border,  however,  may  be  formed  by 
forcing  the  plate  in  at  this  place  with  a  small,  smooth-faced  stamp 
or  tracer,  shaped  to  the  angle  of  the  groove,  passing  round  the 
chamber  and  carefully  forcing  the  plate  in  with  the  stamp  and  a 
small  hammer  or  mallet  until  a  somewhat  sharp  and  abrupt  angle 
is  obtained  to  the  palatal  edge  of  the  chamber.  After  the  chamber 
is  as  perfectly  formed  as  possible  in  this  way,  the  plate  should  be 
well  annealed  and  again  swaged  to  correct  any  partial  deformity 
occasioned  by  stamping  the  chamber. 

The  Soldered  Air-chamber. — A  still  more  perfectly  defined 
angle  may  be  given  to  the  borders  of  the  chamber  in  the  following 
manner :  After  swaging  the  plate  sufficiently  to  indicate  the  exact 
position  and  form  of  the  chamber,  the  portion  forming  the  latter 
should  be  separated  from  the  main  plate  by  completely  dividing  it 
with  a  saw,  or  small,  sharp,  chisel-shaped  instrument,  cutting  on  a 
line  with  the  groove  around  the  chamber  until  the  latter  is  entirely 
separated.  The  cut  portion  of  the  main  plate  is  then  trimmed 
evenly  with  a  file,  being  careful  not  to  enlarge  the  opening  more 
than  is  required  to  remove  the  irregularities  of  the  edge  formed  in 
cutting.  The  plate,  with  its  central  portion  removed, is  then  placed 
upon  the  die,  when  a  separate  piece  of  gold  cut  to  the  general  form 
of  a  chamber,  but  somewhat  larger  than  the  opening  in  the  main 
plate,  is  adjusted  over  the  chamber,  and  struck  up  with  the  plate 


PARTIAL   DENTURES    HELD    BY    ATMOSPHERIC    PRESSURE. 


20I 


until  the  overlapping  portions  of  the  central  piece  are  forced  down 
upon  the  plate  around  the  margins  of  the  chamber.  It  is  not,  how- 
ever, always  necessary  to  employ  a  separate  piece  of  gold  for  the 
chamber,  as  the  central  portion  cut  from  the  plate  in  the  first 
instance  may  be  sufficiently  enlarged  for  the  purpose.  This  is 
accomplished  by  first  flattening  out  the  detached  portion,  anneal- 
ing it,  and  then  passing  successive  portions  of  its  edges  y-g-  of  an 
inch  or  more  between  the  rollers,  the  latter  being  sufficiently  ap- 
proximated to  produce  a  perceptible  thinning  of  the  margins. 
When  the  entire  border  of  the  chamber  piece  has  been  thus  atten- 
uated and  extended,  it  will  be  found  so  much  enlarged  that,  when 
adjusted  to  the  die  and  swaged  in  connection  with  the  main  plate, 

Fig.  88. 


its  borders  will  overlap  and  rest  upon  the  margins  of  the  opening 
in  the  base,  as  in  the  other  case. 

The  portions  of  the  plate  and  cut  chamber  lying  in  contact  and 
temporarily  secured  in  position  by  means  of  wire  clamps,  as 
shown  in  Fig.  88,  are  now  coated  with  borax  and  pieces  of  solder 
placed  along  the  line  of  union  on  the  lingual  side  of  the  plate,  when 
the  two  pieces,  being  transferred  to  a  bed  of  charcoal,  are  perma- 
nently united  by  flowing  the  solder  with  a  blowpipe.  Sufficient* 
heat  should  be  applied  to  induce  an  extension  of  the  solder 
between  the  two  portions  of  plate,  filling  up  completely  the  gap 
between  them  to  the  edge  of  the  orifice  in  the  main  plate,  forming, 
at  this  point,  a  square  and  well-defined  angle  to  the  margins  of  the 
chamber. 


CHAPTER  XVIII. 

METHOD  OF  OBTAINING  AN  ANTAGONIZING  MODEL  FOR  PARTIAL 
DENTURES;  SELECTING,  ARRANGING,  AND  ANTAGONIZING  THE 
TEETH  ;  INVESTING,  ADJUSTING  STAYS,  SOLDERING,  ETC 

Having  constructed  the  plate  or  base  to  be  used  as  a  support 
for  partial  sets  of  teeth  in  either  of  the  ways  described  in  the 
preceding  chapter,  it  will  be  necessary,  before  arranging  the  teeth 
on  the  plate,  to  secure  an  accurate  representation  of  all  the 
remaining  natural  teeth  of  both  jaws  in  plaster,  preserving  accu- 
rately the  relation  which  these  organs  bear  to  each  other  in  the 
mouth.  This  is  effected  by  what  is  called  an  antagonising 
model,  and  may  be  secured  in  the  following  manner : 

Taking  the  "  Bite." — A  roll  or  strip  of  adhesive  wax  is  first 
attached  to  the  lingual  border  of  the  plate,  and  its  adhesion 
secured  by  holding  the  opposite  side  of  the  plate  for  a  moment 
over  the  flame  of  a  Bunsen  burner  or  spirit-lamp.  The  wax  used 
for  articulating  purposes  should  be  harder  and  more  tenacious 
than  plain  beeswax,  and  may  be  compounded  from  the  following 
formula : 

Beeswax,   i  pound. 

Gum   mastic,    2  ounces. 

Spanish    whiting,     1    ounce. 

The  wax  is  first  melted  in  a  shallow  vessel,  and  the  mastic, 
finely  pulverized,  gradually  added,  and  then  the  whiting,  stirring 
constantly  until  thoroughly  incorporated.  The  rim  of  wax  being 
arranged  on  the  plate,  all  superfluous  portions  overhanging  the 
margins  occupied  by  the  remaining  teeth  are  cut  away ;  the  plate 
may  then  be  placed  on  the  model  and  the  wax  again  trimmed, 
leaving-  it  somewhat  fuller  than  the  outer  circle  of  the  teeth,  and 
from  one  to  three  lines  longer  than  those  immediately  adjoining 
the  spaces.  The  plate,  with  the  wax  attached,  is  then  placed  in  its 
proper  position  in  the  mouth,  and  the  patient  instructed  to  close 
the  jaws  naturally  until  the  remaining  teeth  meet ;  one-third  or 
more  of  the  crowns  of  the  opposing  teeth  opposite  the  spaces  will 

2C2 


ANTAGONIZING  MODELS,  TEETH,  ETC.,  FOR  PARTIAL  DENTURES.    2O3 

thus  be  imbedded  in  the  wax.  A  still  fuller  impression  of  the 
opposing  teeth  may  be  obtained,  if  desired,  by  pressing  the  edges 
of  the  wax  down  upon  the  crowns  with  the  finger. 

The  Mesial  Line. — If  a  series  of  anterior  teeth  are  to  be  re- 
placed, the  mesial  line  of  the  mouth  in  front  should  be  indicated 
upon  the  wax  by  drawing  a  line  vertically  across  the  latter  to 
serve  as  a  guide  in  the  arrangement  of  the  central  incisors  and 
adjoining  teeth.  The  plate  and  wax  are  then  carefully  removed 
from  the  mouth  and  again  placed  upon  the  plaster  model,  the  lat- 
ter having  been  previously  obtained  from  an  impression  of  the 
parts  with  the  plate  in  the  mouth. 

Securing  the  Antagonizing  Models. — The  method  of  securing 
the  antagonizing  models  as  practised  by  many,  is  to  place  the 
model  on  a  slip  of  paper  with  the  plate  and  wax  upward,  and  the 
heel  of  the  model  extended  from  one  to  two  inches  posteriorly 
to  form  an  articulating  surface  for  the  remaining  portion  of 
the  antagonizing  model.  The  added  portion  of  plaster  may  be 
confined  by  a  narrow  strip  of  wax  or  sheet-lead  extending  back 
upon  each  side  of  the  model,  into  which  a  batter  of  plaster  is 
poured  to  the  depth  of  y2  or  y^  of  an  inch.  When  hard,  the 
edges  and  upper  surface  of  the  added  plaster  should  be  trimmed 
smooth,  and  a  crucial  groove,  or  two  or  three  conical-shaped 
holes,  cut  in  the  surface  of  the  latter  to  secure  a  fixed  and  definite 
relation  of  the  two  parts  of  the  model.  The  articulating  surface 
is  then  varnished  and  oiled  to  prevent  the  next  portion  of  plaster 
from  adhering;  the  imprints  of  the  teeth  in  the  wax  are  also  oiled. 
The  open  space  looking  into  the  palatal  vault  should  be  closed 
with  a  sheet  of  softened  wax  to  prevent  the  next  portion  of  plaster 
from  flowing  into  the  cavity  underneath.  A  batter  of  plaster  is 
now  poured  carefully  upon  the  exposed  surface  of  the  wax,  filling 
the  imprints  of  the  teeth  perfectly,  and  extending  back  upon  the 
heel  of  the  model  until  it  acquires  a  depth  of  y2  of  an  inch  or  more. 
When  sufficiently  hard,  the  two  sections  of  the  model  are  separ- 
ated, superfluous  portions  trimmed  away,  and  the  entire  surface  of 
both  pieces  glazed  with  varnish,  and  if  the  manipulations  have 
been  accurate,  this  simple  contrivance  will  exhibit  all  the  parts 
represented  in  plaster  in  precisely  the  same  relative  position  which 
they  occupy  in  the  mouth.  The  writer  feels,  however,  that  a  more 
elegant  and  accurate  method  of  securing  the  antagonizing  model, 


204  MECHANICAL   DENTISTRY. 

is  to  take  a  full  impression  of  the  antagonizing  teeth  in  wax 
or  modeling  compound.  Secure  a  plaster  cast  from  same  and 
adjust  the  two  models  properly  upon  an  articulator. 

Selecting,  Arranging,  and  Antagonizing  the  Teeth. — The  teeth 
of  replacement  should  harmonize,  as  nearly  as  possible,  in  size, 
configuration,  and  color,  with  those  remaining  in  the  mouth ;  and 
when  selecting  teeth  for  any  given  case,  the  operator  should  be 
provided  with  a  sufficient  number  of  sample  teeth  to  meet  every 
requirement,  by  comparison,  in  respect  of  the  various  tints  or  deli- 
cate shades  of  color  characteristic  of  the  natural  teeth  and  gums. 
The  required  size  and  form  of  the  artificial  teeth  may  be  deter- 
mined with  tolerable  accuracy  by  a  comparison  with  those  on  the 
plaster  model,  but  the  form  or  figure  more  ceftainly  by  a  careful 
inspection  of  those  in  the  mouth. 

Although  there  are  almost  limitless  varieties  of  manufactured 
teeth,  both  in  respect  to  form  and  color,  it  is  not  always  possible, 
in  partial  cases,  to  obtain  such  as  will  harmonize  with  the  natural 
organs.  As  to  form,  a  much  closer  resemblance  to  the  natural 
organs  in  immediate  relation  with  those  of  replacement  can  be 
obtained  by  cutting  away  more  or  less  freely  from  the  cutting 
edges  of  the  incisors,  and  the  cusps  of  bicuspids  and  molars,  in 
cases  where  the  natural  teeth  are  much  worn.  The  ground  sur- 
faces may  afterward  be  polished  with  pumice  on  a  buff-wheel,  and 
finished  with  rotten-stone  and  oil.  The  exigencies  of  practice,  in 
respect  of  partial  sets,  will  often  require  the  reshaping  of  ready- 
made  teeth  by  grinding,  and  the  original  form  should  never  be 
preserved  at  the  sacrifice  of  utility  and  appearance. 

To  secure  harmony  of  color  in  the  use  of  manufactured  teeth 
as  found  in  dental  depots  is  not  always  practicable.  There  are 
often  conditions  of  the  natural  organs  associated  with  decay  and 
organic  discolorations  which  it  is  impossible  to  match  with  porce- 
lain teeth  provided  by  manufacturers  for  general  purposes.  Such 
needs  of  the  practitioner  can  only  be  adequately  met  by  selecting 
the  teeth  and  having  them  stained  before  baking  at  the  dental 
depot. 

Grinding  the  Teeth. — A  greater  or  less  change  in  the  form  of 
porcelain  teeth  will  be  required,  in  nearly  all  cases,  in  fitting  them 
to  the  vacuities  in  the  jaw;  and  this  is  more  particularly  so  in 
those  cases  requiring  the  use  of  gum  teeth.  This  alteration  of  form 


ANTAGONIZING  MODELS,  TEETH,  ETC.,  FOR  PARTIAL  DENTURES.    205 

is  effected  by  grinding  away  portions  of  the  tooth  upon  an  emery- 
or  corundum-wheel  attached  to  the  dental  lathe  (Fig.  89).  If  the 
edentulous  portions  of  the  ridge  have  suffered  but  little  change 
of  form  by  absorption,  as  where  the  teeth  have  been  recently  ex- 


tracted, and  plain  teeth  (those  representing  only  the  crowns  of  the 
natural  organs)  are  used,  the  posterior  portions  of  the  base  of  the 
latter  resting  upon  the  margins  of  the  plate  will  only  require  to  be 
conformed  to  the  irregularities  on  the  surface  of  the  base-plate, 
grinding  sufficiently  to  give  them^the  proper  length  and  relative 
position,  while  their  anterior  cervical  portion  is  permitted  to  over- 
lap the  edge  of  the  plate  and  rest  directly  upon  the  gum  in  front  on  a 
line  with  the  adjoining  teeth.  When,  however,  a  considerable  con- 


206  MECHANICAL   DENTISTRY. 

cavity  exists  in  the  ridge  and  external  border,  and  single  gnm  teeth 
are  employed  to  restore  the  customary  fulness  and  contour  of  the 
parts,  the  gum  portion  of  the  tooth  should  be  ground  away  on  its 
posterior  face  sufficiently  to  restore  the  circle  of  the  gum  on  the 
external  border  of  the  alveolus,  and  from  the  base  of  the  tooth 
where  it  rests  upon  the  plate,  to  admit  of  a  proper  relative  position 
of  the  artificial  crown  ;  while  those  portions  of  the  porcelain  gum 
terminating  at  and  adjoining  the  remaining  teeth,  next  the  spaces, 
should  be  formed  with  a  thin  retreating  edge,  where  it  laps  upon 
the  natural  gum,  giving  to  the  parts,  when  the  substitute  is  ad- 
justed to  the  mouth,  the  appearance  of  an  unbroken  denture  and  a 
continuous  gum.  When  the  space  to  be  supplied  requires  a  series 
of  two  or  more  single  gum  teeth,  the  latter  should  be  united  to 
each  other  with  the  greatest  care  and  exactness  by  grinding  the 
proximate  edges  of  the  gum  portions  until  the  coaptation  is  such 
as  to  render  the  seams  imperceptible  in  the  mouth.  In  adjusting 
the  porcelain  teeth  to  the. plate,  the  base  of  each  tooth  should  be 
ground  to  rest  as  directly  and  uniformly  on  the  plate  as  possible ; 
for  if  thrown,  in  any  degree,  from  the  plate,  the  whole  strain  in 
mastication  will  come  upon  the  platinum  rivets,  and,  in' a  compara- 
tively short  time,  the  latter  will  either  be  entirely  worn  or  cut  off, 
or  the  artificial  crown  will  be  fractured  on  a  line  with  the  pins. 

Antagonizing  Partial  Dentures. — In  antagonizing  partial  sets 
of  teeth,  the  indications  pointed  out  by  the  customary  closure  of 
the  natural  organs  should  be  followed  as  nearly  as  the  form  and 
position  of  the  opposing  teeth  will  permit.  A  changed  or  abnor- 
mal relation  of  the  teeth  of  both  jaws,  however,  frequently  ren- 
ders it  difficult  to  effect  a  satisfactory  adjustment  of  the  teeth  of 
replacement.  If,  in  the  case  of  the  bicuspids,  for  example,  one  or 
more  teeth  in  the  under  jaw  project  into  a  vacuity  above  to  the 
extent  of  one-third  or  more  of  its  depth,  a  direct  closure  of  the 
substituted  organs  upon  these,  in  the  ordinary  manner,  would  be 
impracticable  without  a  corresponding  shortening  of  the  porcelain 
teeth,  enforcing,  in  such  cases,  an  inharmonious  arrangement,  en- 
tirely inconsistent  with  the  just  requirements  of  the  case.  The 
difficulty  cited,  or  any  of  the  various  modifications  of  it,  may  be 
overcome  wholly,  or  in  part,  in  one  of  two  or  three  ways.  If  the 
teeth  encroaching  upon  tin-  opposite  space  arc  very  loose,  as  is 
frequently  the  ease  with  those  thai  have  become  elongated  from 


ANTAGONIZING  MODELS,  TEETH,  ETC.,  FOR  PARTIAL  DENTURES.    20J 

the  long-continued  want  of  an  adequate  opposing  force,  or  are 
hopelessly  carious  or  otherwise  diseased,  they  should  be  at  once 
removed.  If  they  remain  firm  and  sound,  and  stand  slightly 
within  the  circle  of  the  teeth  of  the  opposite  jaw,  or  if  they  have 
somewhat  of  an  inward  inclination  in  the  arch,  the  vacuity  oppo- 
site may  be  filled  with  non-masticating  teeth,  as  a  cuspid,  on  the 
lingual  side  of  which  an  antagonizing  cusp  of  gold  may  be  con- 
structed, allowing  the  point  of  the  cuspid  to  lap  over  the  labial 
face  of  the  encroaching  tooth  or  teeth ;  or  a  bicuspid,  manufac- 
tured for  the  purpose,  with  the  inner  cusp  near  the  base  of  the 
tooth,  may  be  used  instead.  Additional  room  may  be  provided  in 
such  cases  for  the  overlapping  portion  by  grinding  away  from  a 
corresponding  point  on  the  opposing  tooth.  If,  however,  taking 
the  most  impracticable  case,  the  remaining  teeth  are  sound  and 
firm,  and  stand  vertically  in  the  arch,  closing  between  the  oppos- 
ing teeth  on  a  line  with,  or  somewhat  outside  of,  the  outer  circle 
of  the  latter  (the  elongation  of  such  teeth  being  rather  relative 
than  absolute,  as  where  it  results  from  a  mechanical  wearing  away 
of  the  remaining  antagonizing  teeth  and  a  corresponding  approxi- 
mation of  the  jaws),  the  practitioner  will  be  compelled  either  to 
submit  to  a  mal-arrangement  of  the  teeth  of  replacement  by 
grinding  away  sufficiently  from  their  masticating  surface  to  per- 
mit an  unobstructed  closure  of  the  natural  organs,  or  if  the  re- 
maining teeth  are  few,  and  poor  in  structure,  extract  them,  and 
insert  a  full  denture. 

In  view  of  the  difficulties  which  so  frequently  present  them- 
selves in  connection  with  the  arrangement  of  artificial  teeth  in 
partial  cases,  it  may  not  be  amiss  to  observe  that,  however  essen- 
tial to  the  natural  and  agreeable  expression  of  the  individual  an 
exact  and  harmonious  arrangement  of  the  teeth  of  replacement 
may  be,  this  requirement  should,  in  some  degree,  be  disregarded 
whenever  the  necessities  of  the  patient,  in  respect  of  the  comfort 
and  utility  of  the  appliance  or  the  safety  of  the  natural  organs, 
demand  it; — to  what  extent  appearances  should  be  sacrificed  to 
these  considerations  will  depend  upon  the  peculiar  exigencies  of 
the  case,  and  cannot,  therefore,  be  specifically  stated.  On  the 
other  hand,  it  may  be  observed  that,  if  a  sufficient  number  of  the 
natural  teeth  are  remaining  in  both  jaws  to  enable  the  patient  to 
perform,  with  tolerable  efficiency,  the  act  of  mastication,  the  mere 


208  MECHANICAL   DENTISTRY. 

utility  of  the  substitute  in  regard  to  the  performance  of  this  func- 
tion, may  be  partly  or  wholly  disregarded  whenever  there  is 
sufficient  reason  to  apprehend  that  the  substituted  organs  cannot 
be  antagonized  with  a  view  to  the  comminution  of  food  without 
endangering  the  permanency  and  usefulness  of  the  appliance,  by 
necessitating  the  application  of  forces  unfavorably  directed. 

Investing. — Having  arranged  and  antagonized  the  teeth  as 
accurately  as  possible  on  the  plaster  model,  the  piece  should  be 
placed  in  the  mouth  to  detect  and  remedy  any  faultiness  that  may 
be  found  to  exist  either  in  the  adaptation,  position,  or  antagonism 
of  the  artificial  teeth.  It  is  then  removed  and  imbedded  in  a  mix- 
ture of  plaster,  sand,  and  asbestos,  in  the  proportion  of  about  two 
parts  of  the  former  and  one  part  each  of  the  latter.  The  body  of 
the  investment  may  be  surrounded  by  a  copper  or  sheet-iron  band 
to  prevent  it  from  breaking  away  while  adjusting  the  stays  or  lin- 
ings to  the  teeth.  All  parts  of  the  plate  and  teeth,  except  the 
lingual  side  of  the  former  and  the  backs  of  the  latter,  should  be 
incased  to  the  depth  of  y2  of  an  inch  or  more,  and  when  the  latter 
is  sufficiently  hard  all  traces  of  wax  from  the  inside  should  be 
carefully  detached  with  suitable  instruments. 

Manner  of  Backing  the  Teeth. — The  piece  is  now  ready  for 
the  adjustment  of  stays  or  backings,  which,  when  permanently 
united  by  soldering  to  the  base  and  teeth,  are  designed  to  sustain 
the  latter  in  position.  These  supports  are  formed  from  plate  some- 
what thicker  than  that  used  for  the  base,  a  heavier  and  stronger 
stay  being  necessary  when  they  are  not  united  laterally,  and  when 
plate  teeth  are  used.  If,  however,  single  gum  or  block  teeth  are 
employed,  and  the  stays  are  joined,  forming  a  continuous  band, 
plate  one-half  thicker  than  that  used  for  the  base  will,  ordinarily, 
impart  adequate  security  to  the  attachment.  A  plain  strip,  corre- 
sponding in  width  with  the  tooth  to  be  lined,  is  cut,  and  the  end 
resting  on  the  main  plate  conformed  accurately  with  the  file,  or 
stone  revolved  by  the  dental  engine,  to  the  irregularities  on  the 
surface  of  the  latter,  and  in  such  a  manner  as  to  permit  the  strip  to 
take  the  direction  of  the  tooth.  The  general  form  of  the  stay  may, 
in  the  first  place,  be  obtained  by  cutting  a  strip  from  a  piece  of 
gold.  The  points  upon  the  stay  to  be  pierced  for  the  admission  of 
the  platinum  pins  may  be  ascertained  by  coating  the  surface  of  the 
former  with  wax  softened  in  the  flame  of  a  spirit-lamp,  and  press- 


ANTAGONIZING  MODELS,  TEETH,  ETC.,  FOR  PARTIAL  DENTURES.    200, 

ing  it  first  against  the  lower  pin,  the  point  of  which  will  be  indica- 
ted by  an  indentation  of  the  wax.  The  backing  is  then  perforated 
at  this  point  with  a  plate-punch,  two  forms  of  which  are  exhibited 
in  Fig.  90,  one  armed  with  a  tongue,  which,  when  the  plate  is 

Fig.  90. 


pierced,  forces  the  latter  from  the  punch.  The  strip  is  then  reap- 
plied to  the  upper  pin,  and  the  second  hole  obtained  in  like  manner 
as  the  first.  Instead  of  using  wax,  the  ends  of  the  rivets  may  be 
stained  with  some  pigment,  which  will  show  the  points  to  be 
pierced  in  the  backing. 

The  stay  should  be  adapted  accurately  to  the  face  of  the  tooth  ;  it 
is  then  cut  to  the  proper  length,  reaching  nearly  or  quite  to  the 
point  of  the  tooth,  and  shaped  with  a  file  and  stone  to  the  general 
form  of  the  crown.  When  the  backings  are  to  be  united,  they 
should  be  formed  with  a  shoulder  at  a  point  corresponding  with 
the  neck  of  the  tooth,  and  the  proximate  edges  below  united 
closely  by  squares  edges,  or  the  latter  may  be  beveled  and  made 
to  lap  upon  each  other.    The  process  of  soldering  will  be  greatly 

14 


2IO  MECHANICAL   DENTISTRY. 

facilitated,  and  the  piece  will  be  more  easily  and  artistically 
finished,  by  securing,  in  the  first  instance,  a  perfect  coaptation  of 
all  the  parts  which  are  ultimately  to  be  united.  The  sides  of  the 
holes  in  the  stays  facing  the  plate  should  now  be  enlarged  or  coun- 
tersunk with  a  spear-shaped  or  conical  bur-drill,  and  when  applied 
to  the  teeth  the  projecting  ends  of  the  platinum  pins  are  cut  off 
even  with  the  backings,  and  then  split  and  spread  apart  with  a 
small  chisel-shaped  instrument ;  a  head  will  thus  be  formed  to  the 
rivets  when  solder  is  fused  upon  them,  which  will  prevent  them 
from  drawing  from  the  backings. 

The  Soldering  Process. — All  the  lines  of  union  between  the 
several  pieces  should  next  be  well  scraped,  exposing  a  clean, 
bright,  metallic  surface  to  the  solder  (see  Principles  of  Soldering, 
page  65)  ;  the  seams  are  then  coated  with  borax,  ground  or  rubbed 
in  clean,  soft  water  to  about  the  consistency  of  cream  ;*  after 
which  small  pieces  of  solder  are  placed  along  the  joints  and  over 
the  points  of  the  platinum  pins.  The  piece  thus  prepared  is  now 
placed  in  the  furnace  or  ordinary  fireplace,  in  order  to  heat  the 
entire  mass  preparatory  to  soldering.  The  fuel  most  proper  for 
this  purpose  is  charcoal,  either  alone  or  combined  with  coke,  the 
latter  being  preferable  for  the  reason  that  charcoal  alone  is  more 
quickly  consumed,  and  burning  away  more  rapidly  underneath, 
the  piece  is  more  liable  to  drop  to  the  bottom  of  the  furnace.  The 
fuel  should  be  broken  into  small  pieces  and  built  up  around  the 
borders  of  the  investment  in  order  that  all  parts  of  the  latter  may 
be  uniformly  heated.  The  heating  process  should  be  conducted 
gradually,  for  if  the  piece  to  be  soldered  is  subjected  suddenly  to 
a  high  heat,  the  plaster  will  be  displaced  by  the  too  rapid  evolu- 
tion of  vapor,  and  the  integrity  of  the  porcelain  teeth  will  be  en- 
dangered. The  piece  may  be  allowed  to  remain  in  the  fire  until 
the  plate  acquires  a  visible  red  heat,  when  it  should  be  removed, 
placed  on  a  suitable  holder,  and  the  solder  fused  with  the  blow- 
pipe. A  broad,  spreading  flame  should  first  be  thrown  over  the 
entire  surface  of  the  plate  and  border  of  the  plaster,  until  the  tem- 
perature of  the  entire  mass  is  nearly  that  required  to  fuse  the  sol- 

*  Slate  is  often  used  for  this  purpose,  but  is  unfit,  as,  in  rubbing  the  borax, 
loosened  particles  of  the  former  become  mixed  with  the  latter  and  impede  the  flow 
of  the  solder,  and  becoming  entangled  render  it  unclean  and  porous.  Ground 
glass  or  a  porcelain  slab  is  the  best  for  the  purpose. 


ANTAGONIZING  MODELS,  TEETH,  ETC.,  FOR  PARTIAL  DENTURES.    211 

der,  and  which  is  indicated  by  the  latter  settling  and  contracting 
upon  itself.  A  small  pointed  flame,  carefully  controlled,  with  very 
slight  pressure  upon  the  bellozvs,  may  then  be  concentrated  upon  a 
particular  point,  as  at  the  heel  of  the  plate  on  one  side,  passing 
round  from  tooth  to  tooth  until  all  the  parts  are  completely  united 
and  the  solder  is  well  and  uniformly  diffused. 

Having  united  the  teeth  to  the  plate,  the  piece  may  be  allowed 
to  cool  gradually,  or  it  may  be  plunged,  after  the  lapse  of  a  few 
minutes,  into  boiling  water  without  risk  of  injury  to  the  teeth. 
When  cool,  the  plaster  is  removed  and  the  plate  placed  in  the  acid 
bath  (a  solution  of  equal  parts  of  sulphuric  acid  and  water),  where 
it  may  be  allowed  to  remain  until  the  discoloration  of  the  plate 
and  the  remains  of  the  vitrified  borax,  incident  to  the  soldering, 
are  removed,  or  it  may  be  put  into  a  small  copper  vessel,  partly 
filled  with  the  same  solution,  and  boiled  for  a  few  minutes.  After 
removing  the  plate  from  the  acid,  it  should  be  boiled  for  five  or 
ten  minutes  in  a  solution  of  chlorid  of  soda,  or  common  salt  and 
water,  to  remove  thoroughly  all  traces  of  the  acid. 

The  Finishing  Process. — Superfluous  portions  of  solder  are 
now  to  be  removed,  and  this  at  first  may  be  more  quickly  accom- 
plished by  the  use  of  burs  and  stones  of  various  forms  and  sizes 
attached  to  the  dental  engine.  After  the  rougher  and  more 
redundant  parts  are  thus  cut  away,  any  remaining  irregularities 
upon  the  surface  may  be  further  reduced  with  sand-paper  or 
emery-discs.  Then,  with  a  rapidly-revolving  brush  attached  to  a 
foot-lathe,  the  final  polish  or  luster  may  be  imparted  by  the  use, 
first,  of  finely-powdered  pumice-stone,  followed  by  Spanish  whit- 
ing, or  prepared  chalk,  and  then  rouge  mixed  with  water  or  alcohol. 

In  the  final  adjustment  of  the  finished  piece  to  the  mouth,  and 
after  any  additional  change  in  the  form  of  the  teeth  necessary  to 
secure  the  most  perfect  antagonism  has  been  made,  the  patient 
should,  in  all  cases  of  partial  dentures,  receive  explicit  directions 
in  regard  to  the  general  care  and  management  of  the  appliance 
and  the  remaining  natural  teeth.  Ordinarily,  there  will  be  but 
little  difficulty  experienced  by  the  patient  in  the  immediate  and 
successful  use  of  a  substitute  supported  in  the  mouth  by  clasps,  or 
any  equivalent  means;  but  in  the  case  of  atmospheric-pressure 
plates,  the  patient  should  be  candidly  advised  of  the  probable 
want  of  stability  incident  to  the  first  use  of  the  appliance,  and  the 


212  MECHANICAL   DENTISTRY. 

consequent  annoyance  which  in  many  cases  follows  its  occasional 
displacement  in  mastication  until  such  time  as  the  adaptation  of 
the  several  parts  to  each  other  are  perfected,  and  the  patient  has 
acquired  a  habit  of  controlling  and  directing  the  forces  applied  to 
the  substitute.  The  time  necessary  to  accomplish  these  results 
will  depend  much  upon  the  form  and  condition  of  the  mouth,  a 
favorable  or  unfavorable  antagonism,  the  adaptation  of  the  plate, 
and  the  aptitude  and  temper  of  the  patient.  It  will  be  prudent 
and  but  just  to  the  patient  to  state  that  the  complete  utility  of  an 
appliance  sustained  by  atmospheric  pressure  will  not,  probably, 
be  realized  in  less  time  than  from  one  to  two  weeks,  and  this  esti- 
mate of  time,  in  a  majority  of  cases,  will  be  fully  justified  by  expe- 
rience in  the  cases  under  consideration. 

The  importance  of  thorough  and  absolute  cleanliness  of  the 
substitute  and  remaining  natural  teeth,  and  the  reasons  therefor, 
should  be  clearly  stated ;  and  the  comfort,  utility,  and  durability 
of  the  artificial  fixture,  as  well  as  the  safety  of  all  the  remaining 
natural  organs,  will  depend,  in  a  great  measure,  upon  the  fidelity 
of  the  patient  with  respect  to  the  observance  of  these  injunctions. 
In  those  cases  especially  where  clasps  are  used,  the  substitute 
should  invariably  be  removed  after  each  meal  and  cleansed,  while 
the  teeth  clasped  should,  at  the  same  time,  be  freed  from  deposits 
of  food  or  other  foreign  substances  with  a  brush,  and  other  means 
usually  recommended  for  the  purpose. 


CHAPTER  XIX. 

ENTIRE  DENTURES. 

Preliminary  Observations. — Before  proceeding  to  describe  in 
detail  the  mechanical  processes  or  manipulations  concerned  in 
the  construction  of  entire  dentures,  unnecessary  repetition  will 
hereafter  be  avoided  by  first  considering,  in  this  place,  certain 
underlying  principles  and  fundamental  requirements  which  are 
common  to  all  the  various  distinct  methods  of  replacement  in 
edentulous  cases.  This  preliminary  treatment  of  the  subject  may 
be  comprehended  under  two  general  heads:  (i)  A  consideration 
of  the  principles  and  attendant  phenomena  involved  in  the  appli- 
cation of  the  forces  commonly  utilized  as  a  means  of  attachment ; 
and  (2)  esthetic  requirements  in  the  selection  and  arrangement  of 
the  teeth  of  replacement.  There  are  two  forces  in  nature  utilized 
in  the  retention  of  entire  dentures,  notably  in  upper  cases, — 
atmospheric  pressure  and  adhesion.  We  shall  consider,  first,  some 
of  the  attributes  and  phenomena  characteristic  of  these  forces, 
and  then  endeavor  to  make  some  practical  applications  of  them  in 
elucidation  of  the  subject  in  hand. 

Adhesion  may  be  defined  as  the  force  by  which  the  particles  of 
different  bodies  stick  together,  in  contradistinction  to  cohesion, 
which  is  the  force  that  holds  the  molecules  of  the  same  body 
together.  There  are  several  kinds  of  adhesion,  but  our  present 
purpose  only  contemplates  those  which  relate  to  the  adhesion  of 
solids  to  solids,  and  fluids  to  solids. 

The  adhesion  of  solids  to  solids  is  illustrated  by  pressing  to- 
gether two  plates  of  glass  or  metal  having  perfect  occluding  sur- 
faces, when  they  will  be  found  to  adhere  with  force  enough  to 
support  not  only  the  lower  plate,  but  some  additional  weight. 
Very  delicate  tests  have  been  made  by  which  the  adhesive  force 
is  accurately  measured.  An  important  practical  fact,  in  this  con- 
nection, has  been  well  established,  which  has  a  direct  bearing  on 
the  subject  we  are  considering,  namely,  that  the  tenacity  with 
which  such  plates  adhere  to  each  other  is  not  in  any  manner  due 

213 


214 


MECHANICAL   DENTISTRY. 


to,  but  wholly  independent  of,  any  force  exerted  by  the  pressure 
of  the  atmosphere,  as  was  supposed  by  some  of  the  earlier  experi- 
menters. The  fact  alluded  to  was  conclusively  proven  by  sus- 
pending the  plates,  the  lower  one  of  which  was  weighted,  in  the 
vacuum  of  an  air-pump,  in  which  case  the  plates  still  remained 
adherent.  Examples  of  this  adhesive  force  as  affecting  solids 
might  be  almost  indefinitely  multiplied. 

The  force  of  adhesion  of  solids  to  liquids  is  not  less  pronounced. 
When  a  polished  plate  is  suspended  on  a  delicately  constructed 
balance,  and  brought  carefully  down  on  the  surface  of  a  liquid, 
completely  excluding  the  air,  adhesion  will  take  place,  the  force  of 
which  will  be  modified  by  the  kind  of  liquid  in  contact  with  the 
plate.  It  has  been  ascertained  by  careful  experiment  that  the  ad- 
hevise  force  of  a  polished  plate  of  agate,  one  inch  in  diameter,  in 
contact  with  water,  is  25  grains ;  sulphuric  acid,  29 ;  hydrochloric 
acid,  25;  solution  of  saltpeter,  23;  of  lime,  21;  almond-oil,  16; 
petroleum,  16;  turpentine  and  alcohol,  15;  ether,  10.  Where,  as 
often  happens,  drops  of  the  liquid  adhere  to  the  plate  when  separ- 
ated, it  proves  that  the  adhesion  of  the  liquid  to  the  solid  is 
stronger  than  the  cohesion  of  the  liquid  itself,  and  that  the  num- 
bers obtained  in  these  experiments  express  rather  the  cohesion  of 
particles  of  the  liquid  which  were  separated  by  the  weight,  than 
the  adhesion  of  the  plate  to  the  liquid.  As  in  the  case  of  adhesion 
of  solids  to  solids,  it  was  formerly  claimed  by  some  that  adhesion 
in  these  cases  was  due  to  atmospheric  pressure,  but  that  was  dis- 
proved in  the  same  manner  as  the  other.  Perfect  exclusion  of  air 
is  essential  to  the  operation  of  this  force,  a  suggestive  fact  in  con- 
nection with  the  adaptation  and  retention  of  entire  dentures. 

Atmospheric  pressure  is  that  force  exerted  by  the  air  by  reason 
of  its  gravity,  one  of  its  mechanical  properties  being  zvcight,  which 
renders  it  amenable  to  the  same  law  of  attraction  that  affects  all 
other  bodies  similarly  endowed.  It  exerts  a  pressure  not  only 
downward,  but,  according  to  the  law  of  fluids,  sideways,  upward, 
etc.,  as  by  the  mobility  of  fluid  particles  any  pressure  is  trans- 
mitted in  all  directions.  Superadded  to  gravity  is  its  clastic  force, 
a  property  which,  like  all  gaseous  bodies,  it  possesses  in  a  remark- 
able degree.  This  property  is  familiarly  demonstrated  by  filling 
.-1  bladder  with  air  and  exposing  it  to  rarefied  air  at  a  great  height. 
The  external  pressure  of  the  atmosphere  at  such  an  altitude  being 


ENTIRE   DENTURES.  21  5 

diminished,  the  air  within  tends  to  expand  to  the  same  degree  of 
rarity  as  that  without,  and  with  such  force  as  to  burst  the  bladder. 
The  partial  displacement  of  air  by  compression  within  a  diving- 
bell  by  the  pressure  of  water  at  a  low  depth,  and  the  forcible  ex- 
pulsion of  the  intruding  water  as  the  bell  is  brought  to  the  sur- 
face, not  only  illustrates  its  elasticity,  but  its  impenetrability  also, 
or  its  property  of  preventing  another  body  from  occupying  the 
space  where  it  is.     There  are  many  other  examples  of  the  press- 
ure of  the  atmosphere  and  the  force  exerted  by  virtue  of  its  elas- 
tic property,  but  those  of  most  interest  and  consequence  to  the 
prosthetic  specialist  relate  to  their  effects  on  the  human  organism. 
It  is  estimated  that  the  force  exerted  by  the  pressure  of  the  atmos- 
phere on  the  body  of  a  mediurn-sized  man  must  be  about  15  tons, 
a  force  sufficient  to  crush  and  destroy  him  if  applied  only  to  the 
external  portions  of  the  body.     Such  pressure,  however,  is  neu- 
tralized and  rendered  harmless  by  counter-pressure  from  within ; 
a  result  due  to  the  elasticity  of  the  air,  which  exerts  a  force  every- 
where and  in  all  directions  alike,  from  the  external  parts  inwardly, 
and  from  those  within  outwardly.     The  tendency  in  nature  every- 
where is  toward  the  establishment  of  an  equilibrium  of  atmos- 
pheric pressure,  and  when  these  balanced  forces  are  disturbed, 
unusual  and  characteristic  phenomena  follow.     If,  as  in  the  case 
of  "  cupping,"  the  external  pressure  of  the  atmosphere  is  removed 
by  the  formation  of  a  vacuum,  the  elastic  force  of  the  air  operat- 
ing  from    within,    and    meeting   no    counter-force    at    the    point 
cupped,  will,  by  virtue  of  its  inherent  elastic  energy,  force  the  soft 
tissues  into  the  body  of  the  cup  as  the  result  of  this  tendency  to 
an  equilibrium.     The  latter  occurs   as   soon   as   the   unoccupied 
space  forming  the  vacuum  is  filled  with  the  tissues,  when,  the 
accustomed  balance  of  forces  being  restored,  the  cup  will  loosen 
and  fall  off.     If  the  disturbance  of  the  equilibrium  of  forces  act- 
ing from  without  and  within  is  general,   as  in  the  case  of  an 
aeronaut  in  a  balloon  at  great  heights,  the  result  of  this  tendency 
may,  and  often  has,  put  life  in  jeopardy  by  expansion  of  the  inter- 
nal organs.     On  the  contrary,  the  body  exposed  to  greatly  in- 
creased external  pressure  of  the  air,  as  when  the  latter  is  con- 
densed in  the  diving-bell  at  low  depths,  or  in  caissons  employed 
in  forming  a  foundation  of  subaqueous  structures,  the  results  may 
be  equally  harmful  or  fatal  by  compression  of  the  internal  organs. 


2l6  MECHANICAL   DENTISTRY. 

The  Application  of  Atmospheric  Pressure  and  Adhesion  in  the 
Retention  of  Artificial  Dentures. — The  general  proposition  that, 
in  the  case  of  entire  dentures,  retention  of  the  plate  in  place  by 
atmospheric  pressure  presupposes  a  vacuum  obtained  by  exhaus- 
tion of  the  air  from  a  cavity,  of  whatever  form,  located  somewhere 
between  the  plate  and  the  mucous  surfaces  on  which  the  latter 
rests,  and  that  such  cavit}^  implies  space.  Whenever,  therefore, 
a  dental  appliance  of  the  kind  under  consideration  is  in  uniform 
contact  at  all  points  with  the  parts  in  the  mouth,  it  is  manifestly 
improper  to  speak  of  it  as  being  held  in  place  by  atmospheric 
pressure,  or  to  designate  it  as  an  "  atmospheric-pressure  plate." 
Uniform  contact  implies  perfect  continuity  between  the  plate  and 
the  parts  on  which  it  rests,  and  this  necessarily  precludes  the  idea 
of  space,  and  without  space  a  vacuum  is  impossible,  and  in  the 
absence  of  the  latter,  the  atmosphere,  as  we  shall  endeavor  to 
show,  is  wholly  inoperative  as  a  retaining  force.  To  comprehend 
the  matter  intelligently,  we  must  not  lose  sight  of  the  important 
central  fact  that  the  atmosphere,  in  its  undisturbed  condition, 
exerts  an  equal  pressure  in  all  directions,  a  property  largely  due 
to  its  elasticity,  and  that  in  obedience  to  this  law,  in  its  operation 
upon  the  human  organism,  the  force  exerted  from  without  inward 
is  exactly  counterbalanced  by  the  same  force  acting  from  within 
outward,  thus  establishing  an  equilibrium  of  the  counteracting 
forces,  and  a  consequent  neutralizing  of  pressure  at  the  surface. 
This  equalized  force  is  an  essential  condition  of  human  well-being 
and  of  human  life,  as  has  been  heretofore  stated  and  demonstrated 
by  examples.  The  absurdity,  therefore,  of  attributing  the  reten- 
tion of  substitutes,  adapted  in  this  manner  to  the  mouth,  to  the 
pressure  of  the  atmosphere  is  apparent.  There  can  be  no  reason- 
able question  but  that  substitutes  so  applied  are  held  in  situ  by 
that  force  manifesting  itself  in  adhesion.  In  all  cases  where  the 
plate  or  other  base  is  accurately  adapted  to  the  entire  mucous 
surfaces,  and  the  air  thoroughly  excluded,  the  essential  condi- 
tions favoring  its  retention  by  adhesion  is  secured,  namely,  per- 
fect contact  of  a  solid  with  the  fluids  with  which  the  mucous 
surfaces  are  constantly  bathed. 

Let  us  now  consider,  as  briefly  as  possible,  the  manner  in  which 
air-pressure  acts  as  a  retaining  force  when  applied  to  cavity- 
plates,  and  in  the  same  connection  some  of  the  phenomena  result- 
ing from  such  action. 


ENTIRE   DENTURES.  2.1J 

When  a  plate,  provided  with  a  cavity  or  chamber,  is  applied  to 
the  mouth,  two  concurrent  phenomena  are  observed :  the  imme- 
diate and  forcible  attachment  of  the  plate  to  the  mucous  surfaces, 
and  the  obtrusion  of  the  soft  tissues  into  the  space  from  which 
the  air  has  been  exhausted.  The  first  is  due  to  the  external  press- 
ure of  the  atmosphere,  the  latter  to  the  same  force  acting  from 
within.  Here,  again,  it  is  essential  to  remember  the  fundamental 
fact  that  atmospheric  pressure  acts  equally  in  all  directions.  The 
phenomena  to  which  attention  has  been  called,  in  the  case  of  an 
applied  cavity-plate,  are  the  result  of  a  disturbance  of  these  ordi- 
narily balanced  forces.  When  a  vacuum,  partial  or  complete,  is 
formed  by  exhaustion  of  air  from  the  chamber,  the  external  press- 
ure of  the  air  meeting  with  a  diminished  counter-resistance  from 
within,  by  reason  of  the  vacuum,  forces  the  plate  against  the 
parts,  while  at  the  same  time  the  atmospheric  pressure  acting 
from  within  outwardly,  meeting  with  a  like  diminished  resistance 
at  the  surface  embraced  within  the  limits  of  the  chamber,  forces 
the  soft  tissues  into  the  chamber.  Thus  we  find  displayed  the 
universal  tendency  to  an  equilibrium  of  atmospheric  pressure, 
and  a  practical  illustration  of  nature's  proverbial  abhorrence  of  a 
vacuum. 

It  is  not  probable  that  a  perfect  vacuum  is  ever  secured  by  the 
means  ordinarily  employed  by  the  patient,  unless,  perhaps,  in  the 
case  of  very  shallow  cavities.  The  moment  any  portion  of  the 
contained  air  is  exhausted,  there  is  instant  and  forcible  pressure 
of  the  plate  upon  the  soft  tissues  immediately  surrounding  the 
chamber,  acting  as  an  effectual  mechanical  impediment  to  further 
egress  of  air.  The  power  to  exhaust  is  therefore  self-limited,  and 
a  partial  vacuum  only  the  result.  Sooner  or  later,  in  a  large  per- 
centage of  cases,  even  this  limited  power  is  rendered  inadequate 
to  secure  any  degree  of  exhaustion  by  the  intrusion  of  tissues 
which,  by  long-continued  and  unrelieved  pressure,  become  in  time 
permanently  hypertrophied. 

The  completeness  with  which  the  chamber  may  become  filled 
with  soft  tissues  will  depend  partly  upon  the  form  of  the  cavity, 
and  partly  upon  the  abundance  and  mobility  of  the  tissues.  If  the 
cavity  is  constructed  with  vertical  walls  and  sharply  defined  mar- 
gins, the  latter,  by  becoming  quickly  imbedded,  will  act  as  a 
mechanical  obstruction  to  any  ready,  sliding  movement  of  the 


2l8  MECHANICAL   DENTISTRY. 

tissues  into  the  chamber.  Plates  so  constructed  adhere  with 
greater  tenacity  and  more  persistency,  especially  when  the  parts 
embraced  are  rigid  and  immobile ;  but  it  is  at  the  cost  of  the  max- 
imum of  injury  which  cavity-plates  are  capable  of  inflicting,  and 
which  is  often,  in  extreme  cases,  characterized  by  rupture  of  the 
superficial  vessels,  wounding  of  the  mucous  membrane,  and  in 
active  inflammatory  conditions  which  not  infrequently  involve  the 
adjacent  tissues.  More  ready  entrance  of  the  tissues  into  the 
chamber  occurs  where  the  edges  of  the  latter  are  rounded  and  the 
walls  slope  toward  the  center,  as  in  the  case  of  those  that  are 
swaged,  but  this  form  is  at  the  expense  of  the  retaining  force, 
since  atmospheric  pressure  from  without  is  always  diminished  in 
proportion  as  the  cavity  becomes  filled  in  with  the  tissues,  and 
ceases  entirely  when  a  vacuum  no  longer  exists.  The  facility 
with  which  the  chamber  will  become  occupied  is  greatly  increased 
when  the  soft  tissues  are  in  excess,  their  softness  and  mobility 
offering  but  a  feeble  resistance  to  the  atmospheric  pressure  from 
within,  in  which  case  the  cavity  soon  becomes  partly  or  wholly 
occupied  by  them,  and  what  retaining  force  was  originally  secured 
by  atmospheric  pressure  will,  in  a  comparatively  short  time,  be- 
come greatly  impaired  or  wholly  inoperative. 

When  it  is  remembered  how  transitory  are  the  uses  of  so-called 
"  air-chambers,"  and  how  capable,  under  ordinary  circumstances, 
they  are  of  inflicting  serious  injury  upon  the  delicate  tissues  of  the 
mouth,  there  would  seem  to  be  no  sufficient  reason  or  justification 
for  their  employment,  except  possibly  in  rare  and  exceptional 
cases.  Experience  has  amply  demonstrated  that  equally  secure  and 
much  more  enduring  attachment  of  the  substitute  may  be  obtained  in 
the  utilisation  of  adhesive  force  alone — a  means  of  retention  wholly 
exempt  from  the  harmful  consequences  that  too  often  follow  the 
application  of  atmospheric  pressure  consequent  on  the  formation 
of  a  vacuum. 

There  are,  however,  many  cases  where  spaces  or  cavities  may 
be  employed  to  advantage  for  the  purpose  of  securing,  through 
the  temporary  pressure  of  the  atmosphere,  increased  stability  of  a 
dental  appliance  subjected  to  the  forces  applied  in  mastication. 
There  are  associated  conditions  of  the  mouth  which,  in  their  nor- 
mal and  undisturbed  relation  to  each  other,  prevent,  to  some  ex- 
tent, a  uniform  or  equalized  bearing  of  the  substitute  upon  the 


ENTIRE   DENTURES.  2IO, 

parts  to  which  it  is  applied.  These  conditions  relate  to  unequal 
hardness  and  softness  of  the  tissues,  and  a  consequent  inequality 
of  resistance  to  pressure.  Thus,  if  the  ridge  is  relatively  softer 
and  more  compressible  than  the  central  portion  of  the  arch,  the 
plate,  when  force  is  applied  over  the  ridge,  will  "  ride  "  upon  the 
central  portion,  as  upon  a  pivot-point,  and  thus  raise  or  detach  the 
plate  from  the  ridge  on  the  opposite  side.  This  is  called  "  rock- 
ing "  of  the  plate,  the  action  being  illustrated  in  the  sport  famil- 
iarly known  as  "  see-sawing."  The  remedy  for  this  consists  in 
securing  a  space  between  the  central  portion  of  the  roof  of  the  mouth 
and  the  corresponding  portions  of  the  plate,  so  that  when  the  substi- 
tute is  applied  to  the  mouth  and  the  air  exhausted,  the  greatest  press- 
ure will  be  expanded  upon  the  ridge,  and,  by  compression,  equalise 
the  resistance.  This  space,  when  the  plastic  vegetable'  bases  are 
used,  is  obtained  by  scraping  away  from  the  impression  at  the 
required  points ;  raising  the  central  portions  of  the  plaster  model 
with  sheet-lead  of  proper  form  and  thickness ;  or  by  trimming 
away  from  the  palatal  surface  of  the  finished  piece.  In  the  case 
■of  swaged  plates,  the  shrinkage  of  the  metallic  die  will  ordinarily 
afford  the  required  space. 

In  cases  where  there  is  approximate  uniformity  of  hardness  of 
the  ridge  and  central  line  of  the  arch  extending  antero-posteriorly, 
associated  with  soft  and  yielding  tissues  filling  the  fossae  on  either 
side  and  extending  some  distance  up  the  lateral  walls  of  the  arch, 
it  is  customary,  in  order  to  equalize  the  pressure  of  the  plate,  or 
rather,  to  secure  uniformity  of  resistance  to  such  pressure,  to 
scrape  away  from  such  portions  of  the  plaster  model  as  corre- 
spond with  the  softer  tissues,  thus  securing  in  the  finished  piece 
an  increased  convexity  or  fulness  which,  on  application  of  the 
substitute,  exerts  a  compressing  force  at  such  points,  superadded 
to  that  obtained  either  by  atmospheric  pressure  or  adhesion.  It 
may  be  reasonably  objected  to  this  mode  of  procedure  that  the 
augmented  compressing  force  thus  applied,  being  continually  an- 
tagonized by  the  inherent  elastic  force  of  the  tissue  pressed,  must 
inevitably  tend  to  weaken  the  attachment  of  the  substitute,  and 
that  such  repelling  force  will  continue  to  act,  in  a  diminishing 
degree,  no  doubt,  until,  from  long-continued  pressure,  such  of  the 
tissues  as  are  not  displaced  will  become  absorbed  or  atrophied. 
The  objection  is  emphasized  by  the  further  fact  that,  in  such 


220  MECHANICAL   DENTISTRY. 

cases,  the  absorption  is  always  preceded  and  accompanied  by 
forcible  displacement  of  superabundant  tissue  into  the  soft  palate, 
inducing  more  or  less  irritation  and  ultimate  chronic  tumefaction 
of  the  displaced  tissue  at  the  posterior  margin  of  the  plate.  The 
prevalent  fallacy  that  the  tissues  thus  subjected  to  pressure  are 
condensed  thereby  has  been  considered  in  the  initial  portion  of  the 
chapter  on  Impressions. 

Xo  device  will,  we  believe,  so  effectually  and  satisfactorily  ful- 
fil the  requirements  of  the  cases  last  mentioned  as  the  one  that 
provides  for  displacement  of  the  tissues  within  the  limits  of  the 
plate  itself.  This  may  be  done  by  securing  a  graduated  space, 
including  a  large  part  of  the  palatal  vault.  This  space  should 
not  be  in  the  form  of  a  cavity  with  defined  walls,  but  should 
slope  gradually  toward  the  periphery  in  such  manner  that  its 
boundaries  shall  be  indistinguishable.  By  a  graduated  cavity  is 
meant  that,  wherever  the  soft  tissues  are  in  excess,  there  should 
be  a  corresponding  depth  of  space  to  provide  for  such  varying 
degrees  of  displacement  as  are  essential  in  the  procurement  of  an 
equalized  resistance  to  the  pressure  of  the  plate.  By  this  method 
there  is  not  only  no  injury  or  objectionable  deformity  inflicted,, 
but  the  attachment  of  the  substitute,  instead  of  being  impaired,  as 
in  the  other  method,  is  maintained  at  first  by  the  full  and  un- 
obstructed force  of  atmospheric  pressure,  and  when,  finally,  the 
required  displacement  of  tissue  is  accomplished,  by  a  filling-in  of 
the  space,  the  best  practicable  adaptation  is  obtained,  and  the 
future  stability  of  the  substitute  as  perfectly  provided  for  as  is 
possible  with  the  resources  at  our  command. 

Esthetic  Requirements  in  the  Selection  and  Arrangement  of 
the  Teeth  of  Replacement. — In  selecting  teeth  for  an  entire  upper 
and  lower  denture,  the  special  requirements  in  regard  to  size, 
form,  and  color,  will  depend  in  a  great  measure  upon  the  com- 
plexion, age,  sex,  and  general  configuration  of  the  face  of  the 
patient.  Every  separate  denture,  therefore,  that  is  constructed 
in  strict  conformity  with  a  faithful  interpretation  of  the  special 
requirements  of  each  individual  case,  will  be  characterized  by 
shades  of  difference  in  color,  form,  size,  and  arrangement  of  the 
teeth  of  replacement.  The  indication  in  the  fulfilment  of  such 
requirements,  broadly  stated,  is,  that  such  selection  of  the  teeth, 
in  any  given  case,  should  be  made  as  will,  when  suitably  arranged, 
most  perfectly  reproduce  the  lost  proportions  of  the  facial  con- 
tour, and  restore  the  characteristic  expression  of  the  individual. 


ENTIRE    DENTURES.  221 

To  accomplish  this  with  fidelity  will  require  a  higher  order  of 
intelligent  discrimination,  and  a  broader  art  culture  than  is  re- 
quired in  cases  where  the  operator  is  aided  by  comparison  of  the 
artificial  with  remaining  natural  teeth,  as  in  partial  dentures.  In 
the  present  case  he  has  no  resources  except  those  that  come  to 
him  through  a  critical  and  conscientious  study  of  the  laws  of  har- 
mony as  displayed  in  the  typical  forms  of  dentures  associated 
with  individual  physiognomy  and  temperament.  Says  Dr.  Eben 
M.  Flagg,  a  thoughtful  writer:  "We  find  that  the  necessity  for 
art  in  dentistry  exists  in  proportion  to  the  hopelessness  of  the 
case.  The  greater  the  amount  of  lost  tissue  to  be  replaced,  the 
greater  the  knowledge  of  natural  form  required  to  properly  effect 
its  replacement.  Beginning  with  the  restoration  of  portions  of 
teeth  through  gold  fillings,  we  come  to  the  loss  of  the  entire 
crown,  and,  finally,  to  that  last  resort,  the  replacement  of  the 
entire  denture.  Knowledge  of  form  and  color,  of  expression, 
character,  and  effect,  now  becomes  imperative  to  the  dentist.  To 
relieve  the  condition  of  his  patient,  the  art  of  the  sculptor  and 
colorist  must  be  studied  with  more  care  than  many  of  us  are  wont 
to  give  it,  while  a  knowledge  of  temperament  and  physiognomy 
becomes  an  important  element  in  our  work." 

"  No  matter  how  anatomically  correct,"  observes  one  of  the 
most  intelligent  contributors  to  the  literature  of  esthetic  dentistry, 
the  late  Dr.  James  W.  White,  "  or  how  skilfully  adapted  for 
speech  and  mastication  an  artificial  denture  may  be,  yet,  if  it  bear 
not  the  relation  demanded  by  age,  temperament,  facial  contour, 
etc.,  it  cannot  be  otherwise  than  that  its  artificiality  will  be  appar- 
ent to  every  beholder. 

"  This  law  of  correlation,  harmony,  running  through  nature, 
attracts  and  enchants  us  by  an  infinite  diversity  of  manifesta- 
tions ;  the  failure  to  recognize  its  demands  by  art  is  correspond- 
ingly abhorrent  to  our  sensibilities. 

"  In  the  social  gathering,  a  lady  who  appreciates  the  law  of  har- 
mony delights  the  eye  by  the  taste  displayed  in  her  attire ;  an- 
other, though  more  elaborately  and  expensively  adorned,  yet  fail- 
ing to  harmonize  the  details  of  her  costume,  attracts  attention 
only  by  the  impression  of  incongruity.  We  hear  frequently  from 
a  lady  who  is  selecting  a  bonnet,  or  from  a  gentleman  purchasing 
a  hat  or  other  article  of  wearing  apparel,  the  question  to  a  friend : 
'  Does  this  become  me?  '  the  query  indicating  the  recognition  that, 
however  exquisite  the  material  or  excellent  the  manufacture  of 


222  MECHANICAL   DENTISTRY. 

the  article,  a  certain  law  of  fitness  prevails,  the  failure  to  comply 
with  which  makes  the  wearer  appear  ridiculous.  We  meet  in  the 
street  one  the  color  of  whose  hair  we  expect,  by  the  law  of  asso- 
ciation, to  be  fair  or  sandy,  and  if  otherwise,  a  wig  or  a  dye  is  in- 
stantly suggested. 

"  There  is  a  relation  between  the  physical  form  and  the  voice, 
from  which  we  are  led  to  infer  in  advance  the  character  of  the 
tones  which  from  any  given  individual  may  be  expected.  This 
law  of  association  in  any  case  having  led  us  to  anticipate  a  bass 
voice,  the  anomaly,  should  a  falsetto  greet  us,  is  almost  ludicrous. 

"  There  is  a  similar  relation  between  other  physical  character- 
istics and  the  teeth.  A  broad,  square  face  or  an  oval ;  a  large, 
coarse-featured  man  or  a  delicately-organized  woman ;  a  miss  of 
eighteen  or  a  matron  of  fifty ;  a  brunette  or  a  blonde — these  and 
other  varieties  present  as  many  differing  types,  with  teeth,  in  size, 
shape,  color,  density,  etc.,  corresponding.  If,  then,  teeth,  corre- 
lated in  their  characteristics  to  those  which  nature  assigns  to  one 
class,  be  inserted  in  the  mouth  of  one  whose  physical  organization 
demands  a  different  order,  the  effect  cannot  be  otherwise  than  dis- 
pleasing to  the  eye,  whether  the  observer  be  skilled  in  perception, 
or  intuitively  recognizes  inharmony  without  understanding  the 
cause." 

Written  or  verbal  instructions  can  do  little  more  than  present 
general  principles  governing  the  selection  of  teeth  for  any  given 
case.  The  completeness  with  which  the  requirements  of  indi- 
vidual cases  are  fulfilled  will  largely  depend  upon  the  operator's 
art  intuitions,  and  his  ability  properly  to  interpret  and  apply  the 
basal  facts  which  an  intelligent  study  of  the  relation  of  physi- 
ognomy and  temperament  to  the  teeth  has  revealed.  The  rela- 
tions of  the  latter  to  the  teeth  have  been  clearly  and  fully  set  forth 
in  tabulated  form  by  Dr.  J.  Foster  Flagg,  which  we  herewith  ap- 
pend. The  first  tabic  relates  to  the  basal  temperaments,  namely, 
bilious,  sanguineous,  nervous,  and  lymphatic,  and  their  general 
indications  ;  the  second,  to  the  teeth  as  indicated  by  temperament. 

A  careful  study  of  these  tables,  the  subject-matter  of  which  is 
by  far  the  most  valuable  contribution  that  has  yet  appeared  in 
connection  with  the  subject  under  consideration,  will  furnish  a 
helpful  means  of  solving  one  of  the  most  difficult  problems  in 
prosthetic  practice. 


ENTIRE   DENTURES.  223 

The  following  editorial,  by  Dr.  James  W.  White,  on  "  Tempera- 
ment in  Relation  to  Teeth,"  suggested,  doubtless,  by  Dr.  Flagg's 
tables,  embodies  not  only  a  discussion  of  the  general  subject  of 
temperaments,  but  some  forcible  and  striking  commentaries  on 
the  importance  and  value,  esthetically  considered,  of  the  indica- 
tions furnished  by  temperamental  characteristics  in  the  intelligent 
choice  of  artificial  substitutes  for  special  cases.  The  importance 
of  the  subject  to  which  the  article  relates  will  justify  its  introduc- 
tion here  without  abridgment : 

"  The  animal  kingdom  is  divided  into  sub-kingdoms,  classes, 
orders,  families,  genera,  species.  A  further  or  sub-division  in- 
cludes in  minor  groups  individuals  whose  salient  characteristics 
are  correspondent  or  similar.  Thus  every  living  creature  has 
certain  physical  peculiarities  by  which  its  position  in  this  classifi- 
cation is  determined.  Man,  as  the  head  of  the  animal  kingdom, 
besides  having  his  place  in  this  general  scale,  is  distinguished  by 
a  still  finer  classification  under  the  denomination  of  temperament 
— an  association  of  several  distinguishing  characteristics,  such  as 
size  and  form  of  body,  complexion,  color  of  the  eyes  and  hair, 
and,  to  a  certain  extent,  the  disposition  and  character  of  the  in- 
dividual. 

"  Temperament  may  be  defined  as  a  constitutional  organization, 
depending  primarily  upon  heredity — national  or  ancestral — and 
consisting  chiefly  in  a  certain  relative  proportion  of  the  mechan- 
ical, nutritive,  and  nervous  systems,  and  the  relative  energy  of 
the  various  functions  of  the  body — the  reciprocal  action  of  the 
digestive,  respiratory,  circulatory,  and  nervous  systems.  The 
stomach,  liver,  lungs,  heart,  and  brain — digestion,  assimilation, 
respiration,  circulation,  and  innervation — are  all  factors  in  the 
differentiation  of  temperament ;  and  according  to  the  congenital 
predominance  of  one  or  the  other,  and  the  relative  activity  of 
these  functions,  is  the  modification  of  the  characteristics  of  the 
individual  which  assigns  him  to  one  or  other  of  the  basal  or  mixed 
temperaments.  Each  temperament  is  the  result  as  well  as  the 
indication  of  the  preponderance  of  one  or  another  of  these  sys- 
tems, and  of  relative  functional  activity. 

"  A  perfect  equilibrium  of  the  different  systems  is  rarely,  if 
ever,  presented  in  any  individual.  One  having  a  balance  of  all 
the  temperaments  would  be  temperamentless,  or  of  no  special 


224  MECHANICAL   DENTISTRY. 

temperament.  It  is  difficult,  in  some  cases,  to  decide  positively 
to  which  variety  a  special  case  belongs,  the  several  temperaments 
being  combined  and  blended  in  such  ever-varying  proportions. 
Not  infrequently  the  indications  are  even  contradictory,  and  the 
blending  of  several  temperaments  requires  a  nice  discrimination 
to  define  the  admixture.  The  primary  elements  of  temperament 
are  susceptible  of  such  manifold  combinations ;  the  determining 
forces  are  so  complex,  and  our  knowledge  of  their  comparative 
values  is  so  limited,  that  no  rule  can  be  given  which  will  not  fail 
in  numerous  instances  to  apply  in  all  respects  to  individual  cases ; 
but  that  there  is  a  general  relation  between  constitutional  quali- 
ties and  external  signs  does  not  admit  of  question. 

"  Temperaments  are  readily  divisible  into  four  basal  classes — 
bilious,  sanguineous,  nervous,  and  lymphatic  (see  tables)  ;  then 
again  into  sub-classes  of  mixed  temperaments — a  combination  of 
two  or  more  of  the  primary  divisions.  In  these  combinations  one 
or  other  of  the  so-called  basal  temperaments  predominates,  and  a 
compound  term  is  used  to  express  the  complexity,  as,  for  instance, 
the  nervo-bilious,  signifying  that  the  bilious  base — the  foundation 
temperament — is  qualified  by  an  admixture  of  the  nervous  ele- 
ment, and  so  throughout  the  series.  Twelve  varieties  of  temper- 
ament, in  addition  to  the  four  basal,  may  thus  be  designated  by 
the  combination  in  pairs  of  the  original  four.  The  admixture  of 
the  peculiarities  of  three  or  of  all  four  of  the  basal  temperaments 
results  in  what  are  denominated  respectively  ternary  and  quater- 
nary combinations,  which  call  for  nice  discrimination  in  diagno- 
sis ;  but  even  such  complexities  are  registered  in  the  size,  form, 
and  color  of  the  dental  organs. 

"  The  value  of  a  practical  application  of  the  study  of  tempera- 
ment in  the  practice  of  dentistry  is  apparent.  That  the  relation 
of  the  teeth  to  temperament  is,  as  a  rule,  ignored  by  those  en- 
gaged in  prosthetic  dentistry  is  evident  in  the  mouths  of  a  ma- 
jority of  those  who  are  so  unfortunate  as  to  be  under  the  neces- 
sity of  wearing  substitutes  for  lost  natural  dentures. 

"  A  certain  law  of  harmony  in  nature  between  the  teeth  and 
other  physical  characteristics  necessitates  respect  to  size,  shape, 
color,  and  other  qualities  in  an  artificial  denture,  in  order  that  it 
shall  correspond  with  other  indications  of  temperament;  and  if 
teeth   correlated   in   their  characteristics   to  those   which   nature 


ENTIRE   DENTURES. 


225 


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ENTIRE    DENTURES. 


227 


assigns  to  one  temperament  be  inserted  in  the  mouth  of  one 
whose  physical  organization  demands  a  different  type,  the  effect 
is  abhorrent.  The  artificiality  of  artificial  teeth  is  the  subject  of 
remark  by  those  who  have  little  or  no  conception  of  the  reason 
therefor — simply  an  instinctive  appreciation  of  the  incongruity 
and  unreality.  It  is  indeed  rare  to  see  a  case  in  which  there  is 
occasion  for  a  moment's  hesitation  as  to  the  fact  of  replacement. 
There  is  no  dental  service  that,  from  the  esthetic  standpoint,  is, 
as  a  rule,. so  illy  performed  as  the  prosthetic.  Thousands  of  den- 
tures are  constructed  which  serve  the  needs  of  the  wearer  for 
speech  and  mastication,  but  which  are,  nevertheless,  deserving  of 
utter  condemnation  as  art  productions.  More  attention  has  been 
paid  to  the.  best  methods  of  restoring  impaired  function — secur- 
ing comfort  and  usefulness  in  artificial  dentures — than  to  a  corre- 
lation of  the  substitutes  to  the  physical  characteristics  of  the 
patient. 

"  What  is  needed  is  such  an  appreciation  of  the  law  of  corres- 
pondence that  the  dentist  can  cipher  out,  as  by  the  rule  of  three, 
the  character  of  teeth  required  in  the  case  of  an  edentulous  mouth 
with  the  same  precision  as  the  comparative  anatomist  can,  from  a 
single  bone,  indicate  the  anatomical  structure  of  the  animal  to 
which  it  belonged.  The  probability  is  that  in  many,  perhaps  in 
most,  of  the  cases  of  incongruous  artificial  dentures  the  fault  is 
not  in  carelessness  or  indifference  of  the  dentist,  but  in  failure  to 
recognize  the  requirements  of  temperament.  A  certain  family 
resemblance  to  each  other  in  a  set  of  teeth  is  considered  essential, 
but  the  adaptability  of  the  set  as  a  whole  to  a  given  case  should 
be  esteemed  of  even  greater  importance.  Especially  is  there  a 
notable  failure  to  recognize  the  color  demanded  by  form.  A  set 
of  teeth  in  which  not  only  the  relative  length  and  breadth,  but 
every  line  and  curve,  characterize  it  as  belonging  to  a  certain  tem- 
perament, is,  in  contravention  of  every  law  of  correspondence, 
made  of  a  color  which  was  never  found  in  nature  associated  with 
such  forms.  Thus  we  see  constantly  such  incongruities  as  the 
association  of  the  massive  tooth  of  the  bilious  temperament  with 
the  pearl-blue  color  belonging  to  the  nervous  temperament,  and 
the  long,  narrow  teeth  of  the  nervous  temperament  of  bronze- 
yellow  color  never  seen  in  the  mouth  of  any  but  those  of  a  bilious 
temperament. 


221 


MECHANICAL   DENTISTRY. 


"  The  trouble  is  not  with  the  manufacturers ;  they  supply  the 
demand.  The  fact  is,  the  requirements  of  the  law  of  correspond- 
ence have  not  been  sufficiently  studied  by  the  profession.  The 
first  study  of  the  dentist  who  aspires  to  the  dignity  of  artist,  when 
proposing  to  replace  a  lost  denture,  should  be  how  to  restore  the 
natural  appearance  of  his  patient,  and  this  can  only  be  effected 
through  an  appreciation  and  observance  of  the  temperamental 
characteristics  and  the  law  of  correspondence  or  harmony.  Age 
and  sex  may  somewhat  modify  the  requirements  in  a  given  case, 

Fig.  91. 


Bilious. 


Sanguineous 


but  tin-  basal  fact  on  which  he  should  proceed  is  temperament. 
A  failure  to  recognize  its  demands  will  result  in  failure — from  an 
esthetic  standpoint." 

Selection  and  Arrangement  of  Artificial  Teeth. — A  knowledge 
of  the  distinguishing  characteristics  of  the  various  temperaments 
and  the  style  of  teeth  which  conform  to  nature's  type  in  the  phys- 


ENTIRE   DENTURES. 


229 


ical  organization  (see  Fig.  91)  marks  the  difference  between  the 
dental  mechanic  and  the  dental  artist ;  and  the  fulfilment  of  the 
highest  art  conceptions  in  the  construction  of  entire  dentures  is 
far  from  being  complete  with  the  mere  selection  of  teeth  in  con- 
formity with  temperamental  and  other  indications.  The  essen- 
tial preliminary  step  is  concerned  chiefly  with  the  form  and  color 
of  substitutes,  but  the  highest  attainments  in  the  art  of  replace- 
ment can  never  be  attained  without  an  intelligent  perception  of 
the  esthetic  requirements  which  have  inseparable  relation  to  the 
arrangement  of  the  teeth  selected  in  strict  conformity  with  the 
same  law  of  harmony  or  correspondence  that'  applies  to  form  and 
color.  The  art  of  arrangement  is  scarcely  less  difficult,  and  cer- 
tainly not  less  important,  than  the  art  of  selection,  and  equal 
judgment  and  discrimination  will  be  required  to  effect  such  an  ad- 
justment of  the  teeth  as  will  most  faithfully  serve  to  restore  the 
facial  contour  and  characteristic  expression  of  the  individual. 
This  will,  in  most  cases,  necessitate  some  deviation  from  the  uni- 
formly symmetrical  or  ideal  relation  of  the  teeth  to  each  other 
characteristic  of  perfect  regularity  of  arrangement,  and  which 
rarely  exists  except  in  connection  with  a  perfectly  balanced  devel- 
opment of  the  jaws  and  teeth,  a  condition  which  may  be  said  to 
be  almost  phenomenal. 

The  kind  or  degree  of  displacement  of  any  particular  tooth  or 
teeth  to  effect  such  irregularity  of  arrangement  as  would  best 
reproduce  the  customary  expression  of  the  individual  in  any  given 
case,  cannot,  of  course,  be  here  indicated.  The  operator  is  neces- 
sarily thrown  upon  his  own  resources  in  determining,  in  this 
respect,  the  necessities  of  individual  cases.  Generally  speaking, 
the  changed  relation  of  the  teeth  is,  in  most  part,  confined  to  the 
six  anterior  teeth,  above  and  below,  as  they  are  most  largely  con- 
cerned in  expression  ;  but  it  may  often  be  extended  to  the  bicus- 
pids and  molars,  which  may  be  displaced  within  or  without  the 
arch,  or  given  an  oblique  position,  with  here  and  there  interdental 
spaces,  some  of  which  may  be  wide  enough  to  suggest  the  loss  of 
the  natural  teeth  at  intervals.  The  central  incisors  may  be  made 
to  overlap  each  other,  with  the  laterals  in  normal  position ;  or  the 
latter  may  be  given  a  position  inside  of  the  circle,  which  will  give 
a  relative  prominence  to  the  centrals  and  cuspids,  or  they  may  be 
partially  rotated  while  retaining  their  regular  position  in  the  arch, 


230 


MECHANICAL    DENTISTRY. 


or  be  made  to  overlap  or  underlap  the  centrals,  in  which  case  the 
latter  may  be  made  to  diverge  somewhat  from  each  other  at  the 
points,  leaving  some  space  between  them.  Figs.  92,  93,  94,  and 
95,  are  given  as  suggestive  both  in  the  selection  of  teeth  and  their 
arrangement. 

There  is  scarcely  any  limit  to  the  capability  of  effecting  mal- 
positions of  the  teeth  of  replacement,  and  this  is  especially  true  of 

Fig.  92. 


those  forms  of  substitution  known  as  continuous-gum  work,  and 
in  the  use  of  celluloid,  either  process,  by  admitting  of  the  use  of 
single,  plain  teeth,  affording  unlimited  opportunities  for  the  op- 
tional placement  of  the  teeth.  In  the  use  of  sectional  gum  teeth, 
many  of  the  forms  of  dental   irregularity  have   been   faithfully 


Fig.  93. 


reproduced  by  manufacturers,  and,  when  selected  with  an  intelli- 
gent apprehension  of  their  fitness  for  any  particular  case,  will 
meet  the  ordinary  wants  of  the  practitioner  in  the  use  of  rubber, 
or  a  metallic  plate-base  with  rubber  or  celluloid  attachment.  The 
minimum  of  capability  in  effecting  irregularity  of  arrangement  is 
attached  to  soldered  work,  where,  as  is  usually  the  case,  single 
gum  teeth  are  employed. 


ENTIRE   DENTURES. 


231 


It  is  possible  often,  when  teeth  have  been  selected  conforming 
as  nearly  as  practicable  to  the  requirements  of  the  case  in  color, 
so  to  change  the  form  of  the  teeth  by  judicious  grinding  of  the 
proximate  surfaces,  cutting  edges  of  the  incisors,  and  the  points 


Fig.  94. 


of  the  cuspids,  and  occluding  surfaces  of  bicuspids  and  molars,  as 
greatly  to  change  the  effect  in  the  mouth,  giving  them  an  harmo- 
nious expression  impossible  in  the  use  of  manufactured  teeth  in 
their  unchanged  form.  Figs.  92  and  93  indicate  the  treatment. 
This  is  particularly  observable  when  they  are  ground  in  imitation 


Fig 


of  the  partial  destruction  of  the  occluding  surfaces  by  erosion, 
a  condition  very  commonly  associated  with  middle  age.  The 
effect  is  still  further  enhanced  by  coloring  the  portions  of  the 
ground  surfaces  in  imitation  of  the  dark  discoloration  usually 


232 


MECHANICAL   DENTISTRY. 


associated  with  exposed  dentine.  This  may  be  readily  done  in 
the  manner  described  in  the  chapter  on  partial  dentures  mounted 
on  metallic  plate-base.  The  same  process  of  coloring  may  also 
be  applied  to  single  porcelain  teeth  representing  absorption  or 
recession  of  the  gum  at  the  cervix,  which  is  always  of  a  darker 
hue  than  the  crown  (see  Fig.  93).  An  additional  device,  some- 
times employed  to  disguise  the  fact  of  artificiality,  is  that  of  intro- 
ducing gold  fillings  into  one  or  more  of  the  front  teeth.  Cavities 
for  this  purpose  are  sometimes  formed  in  porcelain  teeth  at  the 
time  of  baking.  When  these  are  not  readily  procured,  the  opera- 
tor may  easily  improvise  them.  A  dovetailed  slot  may  be  ground 
in  the  proximate  side  of  a  front  tooth  with  suitably  formed  cor- 
undum-discs, or  a  concave  depression  made  and  retaining  pits 
formed  with  a  hard-tempered  steel  drill.  A  correspondent  of  the 
Cosmos  gives  the  following  method  of  using  the  drill :  "  Use  a 
hard-tempered,  spear-pointed  steel  drill  in  the  engine,  and  while 
operating  keep  wet  with  a  solution  of  spirits  of  camphor  and  spir- 
its of  turpentine  in  equal  parts.  The  cutting  will  be  facilitated  by 
giving  the  hand-piece  a  slight  rotary  motion.  If  a  contour  filling 
is  desired,  grind  off  with  the  corundum-wheel  as  much  as  is 
desired  for  '  contour,'  after  which  make  the  retaining  portion  with 
the  drill."  Cavities,  however,  can  be  formed  with  greater  facility 
by  the  use  of  the  diamond  drill. 

With  these  general  reflections  concerning  full  dentures,  we  re- 
turn to  a  consideration  of  the  mechanical  or  manipulative  proc- 
esses concerned  in  the  construction  of  an  entire  denture  attached 
to  a  swaged  metallic  plate  by  soldering. 


CHAPTER  XX. 

ENTIRE   DENTURES    ATTACHED    TO    A   SWAGED    METALLIC    PLATE- 
BASE. 

Method  of  Constructing  an  Entire  Upper  Denture  Mounted  on 
a  Swaged  Metallic  Plate-Base. — The  general  form  and  dimen- 
sions of  the  required  base  to  be  used  as  a  support  for  a  complete 
denture  for  the  upper  jaw  may  first  be  indicated  by  drawn  lines 
upon  the  plaster  model,  and  a  sheet-lead  pattern  obtained  from 
this  is  to  serve  as  a  guide  in  securing  the  form  of  the  plate  to  be 
swaged.  The  plate  should  be  made  sufficiently  ample  in  its  di- 
mensions to  cover  all  the  hard  palate,  the  alveolar  ridge,  and  all 
portions  of  the  external  borders  of  the  latter  not  directly  en- 
croached upon  by  the  muscles  and  reflected  portions  of  the  mu- 
cous membrane  of  the  lips  and  cheeks. 

Before  swaging,  the  plate  should  be  well  annealed,  then  its 
central  portion  is  brought  as  nearly  as  possible  to  the  form  of  the 
palatal  face  of  the  die  with  the  No.  I  or  partial  counter-die  (see 
page  169),  forcing  the  heel  of  the  plate  down  with  suitable  pliers 
and  forceps  in  advance  of  the  portion  covering  the  more  anterior 
concavity  of  the  arch,  preventing  thereby  a  doubling  of  the  pos- 
terior edge  of  the  plate  upon  itself. 

Having  conformed  the  plate  as  nearly  as  practicable  to  the  die, 
with  the  small  counter  and  plate-forceps  constructed  for  the  pur- 
pose (Fig.  96),  it  should  be  placed  between  the  die  and  the  larger 
counters,  which  are  forced  together  with  a  heavy  hammer  until 
a  tolerably  accurate  coaptation  of  the  plate  is  obtained,  the  latter 
being  frequently  annealed  during  the  process  of  stamping  to  ren- 
der it  more  pliable.  At  first  considerable  yielding  and  consequent 
deformity  of  the  counter-die  will  occur ;  hence,  after  partial  swag- 
ing, another  should  be  substituted,  and  the  process  continued  un- 
til the  greatest  possible  accuracy  of  adaptation  is  secured.  If 
the  face  of  the  die  is  marked  by  prominent  and  sharply  defined 
rugae,  or  other  irregularities,  such  points  will,  to  some  extent,  be 
bruised  or  flattened ;  it  will  therefore  be  expedient  in  such  cases, 

233 


234 


MECHANICAL    DENTISTRY. 


and  better,  perhaps,  in  all,  to  finish  the  swaging  with  a  new  and 
unused  die  and  counter,  in  which  case  two  or  three  moderate, 
steady,  and  well-directed  blows  of  the  hammer  will  be  sufficient. 
If  the  plate  is  brought  into  uniform  contact  with  all  parts  of  the 
face  of  the  die,  this  conformity  is  the  only  reliable  test  of  its  adap- 
tation out  of  the  mouth.  In  no  case  will  the  swaged  plate  fit  the 
plaster  model   perfectly,   inasmuch   as   the   unavoidable   contraction 


Fig.  96. 


of  the  die,  however  slight,  will,  especially  in  deep-arched  mouths, 
cause  the  plate  to  bind  on  the  posterior  and  external  borders  of 
the  ridge,  preventing  it  from  touching  the  floor  of  the  palate ; 
while  the  bruising,  though  inconsiderable,  of  the  more  prominent 
points  upon  the  die,  and  a  corresponding  flattening  of  the  plate  at 
such  points,  will  prevent  uniform  contact  of  the  latter  with  the 
unchanged  surface  of  the  plaster  model. 

After  final  swaging,  the  plate  should  be  again  annealed  with  a 
heat  nearly  or  quite  equal  to  that  which  will  be  ultimately  re- 


ENTIRE    DENTURES    ATTACHED   TO    SWAGED    PLATE-BASE. 


235 


quired  in  soldering.  After  this,  any  additional  swaging  should 
be  avoided,  unless  the  plate  warps  in  the  heat,  which  may  be  de- 
termined by  applying  it  to  the  die.  If  any  change  has  occurred, 
it  should  be  reswaged,  and  again  annealed  at  a  high  heat,  and  the 
operation  should  be  repeated,  if  necessary,  until  the  plate  retains 
its  integrity  of  form  after  the  last  annealing.  This  process  of 
final  heating  does  not  apply  to  silver  if  in  the  form  of  a  swaged 
plate,  as  this  metal  invariably  suffers  some  change  of  form  when 
subjected  to  an  annealing  heat. 

Modifications  in  the  Form  of  Plates  for  Entire  Upper  Dentures. 
— Whenever  a  central  air-chamber  is  employed,  it  may  be  con- 
structed in  either  of  the  ways  described  when  treating  of  partial 


Fig.  97. 


Fig.  98. 


atmospheric-pressure  plates.  The  general  form  of  an  entire  up- 
per denture  with  a  central  chamber  is  exhibited  in  Fig.  97.  Other 
modifications  in  the  form  of  cavity-plates  for  full  upper  sets  are 
in  limited  use,  as  where  chambers  are  arranged  one  on  each  side 
of  the  sloping  walls  of  the  palate,  or  directly  over  that  portion  of 
the  ridge  previously  occupied  by  the  anterior  molar  and  the  bicus- 
pids on  each  side,  as  seen  in  Fig.  98,  called  "  lateral  cavity-plates." 
Whatever  their  general  utility  may  be,  cases  doubtless  occur 
where  they  may  be  advantageously  employed ;  separately,  as 
shown  in  the  illustration,  or  in  combination  with  the  central 
chamber,  as  when  any  great  inequality  exists  in  the  hardness  of 
the  ridge  and  palate,  such  as  cannot  be  readily  overcome  by  ordi- 
nary means.  These  lateral  cavities  or  chambers  are  not  cut  out 
and  soldered  as  is  sometimes  done  with  the  central  chambers. 
The  cast,  and  consequently  the  die,  is  raised  or  built  up  slightly 


236  MECHANICAL   DENTISTRY. 

at  these  points,  which  forms  in  the  plate  when  swaged,  the  shal- 
low cavities  shown  in  the  illustration. 

Forming  the  Borders  of  the  Plate. — In  whatever  way  the  plate 
is  formed,  a  notch  or  fissure  of  sufficient  depth  to  receive  and 
permit  an  unobstructed  play  of  the  frenum  of  the  lip  should  be 
formed  in  the  front  part  of  the  plate,  while  the  borders  of  the 
latter  nearly  opposite  the  anterior  molars  on  each  side  should  be 
narrowed  to  prevent  undue  contact  of  its  edges  with  the  folds 
of  the  mucous  membrane  stretching  obliquely  across  from  the 
cheeks  to  the  ridge.  Care  should  also  be  taken  to  trim  away 
from  the  heel  of  the  plate  any  portions  that  might  otherwise  en- 
croach upon  the  soft  palate. 

It  is  only  in  the  fewest  number  of  cases  that  a  rim  can  be 
swaged  to  form  a  groove  or  socket  properly  situated  for  the  re- 
ception of  the  plate  extremities  of  either  single  gum  or  block 
teeth,  as  it  will  usually  be  found  impracticable  to  adjust  the  gum 
extremities  to  the  socket  thus  formed  without  necessitating,  in 
some  degree,  a  departure  from  a  just  arrangement  and  antagon- 
ism of  the  teeth.  Whenever  it  is  thought  best,  therefore,  to  rim 
the  plate,  it  will  generally  be  necessary  to  adjust  and  solder  a 
separate  strip  of  plate  or  wire  along  the  outer  borders  of  the 
plate,  covering  somewhat  the  extreme  edge  of  the  gum,  when 
gum-teeth  are  employed,  and  of  the  pink  rubber-gum,  when  plain 
teeth  are  used. 

Trying  the  Plate  in  the  Mouth. — After  the  plate  has  been 
worked  as  nearly  as  possible  into  the  required  form,  it  should  be 
applied  to  the  mouth  of  the  patient  to  ascertain  the  correctness  of 
its  adaptation  to  the  parts  before  proceeding  further  with  the 
operation.  If  the  adaptation  is  found  imperfect,  the  fault  lies 
either  in  the  impression  or  in  undue  contraction  of  the  die.  In 
the  former  case,  another  impression  should  be  taken,  and  the  plate 
reswaged ;  in  the  latter,  a  less  contractile  metal  or  compound 
should  be  employed  in  the  formation  of  the  die.  To  determine 
the  practical  efficiency  of  the  adaptation  and  adherence  of  an 
atmospheric-pressure  plate,  various  tests  may  be  applied.  The 
coaptation  of  its  borders  to  the  external  walls  of  the  ridge  may 
be  ascertained  by  inspection,  and  the  patient's  sense  of  contact 
or  non-contact  of  its  central  portion  with  the  floor  of  the  palate 
may,  in  some  degree,  be  relied  on  as  evidence  of  the  accuracy  of 


ENTIRE   DENTURES    ATTACHED   TO    SWAGED    PLATE-BASE.  237 

its  adjustment  to  parts  not  visible.  The  tenacity  with  which  the 
plate  adheres  on  the  application  of  direct  traction  cannot  always 
be  relied  upon,  inasmuch  as  a  well-fitting  plate  will  sometimes 
readily  be  dislodged  in  this  manner,  while,  on  the  contrary,  one 
but  illy  adapted  to  the  parts  may  require  considerable  force  to 
separate  it  from  the  jaw  when  acted  on  in  the  same  way.  The  most 
trustworthy  test  of  actual  or  practical  stability  is  firm  pressure  applied 
alternately  over  the  ridge  on  each  side  and  in  front.  If  the  plate 
maintains  its  position  and  remains  fixed  under  repeated  trials  of  press- 
ure applied  in  the  manner  indicated,  the  adaptation  may  be  safely 
relied  on ;  if  it  slides  upon  the  palate  or  is  easily  disengaged  from  the 
mouth,  the  instability  of  the  plate  may  be  referred  in  many  cases,  not 
to  a  want  of  coaptation,  but  to  a  want  of  uniformity  in  the  condition 
of  the  parts  on  which  the  plate  rests.  These  conditions  have  already 
been  sufficiently  considered. 

Method  of  Constructing  an  Entire  Lower  Denture  Mounted 
on  a  Swaged  Metallic  Plate-base. — Aside  from  the  differences  in 
the  form  of  the  plate,  and  the  manipulations  incident  thereto,  the 
process  of  constructing  a  plate  for  the  under  jaw  does  not  differ 
essentially  from  that  already  described  in  connection  with  full  upper 
dentures. 

If  the  lower  plate  is  constructed  from  a  single  lamina  of  gold  or 
other  metal,  it  should  be  somewhat  thicker  than  that  used  in  upper 
cases,  and  should  also  be  of  finer  quality,  as  the  additional  thickness 
of  the  plate  and  the  peculiar  form  of  the  inferior  maxilla  render  a 
greater  degree  of  pliancy  necessary  in  swaging  it  to  the  form  of  the 
ridge.  The  internal  border  of  the  plate  should  usually  be  doubled — 
either  by  turning  the  edge  over  in  swaging,  or  by  soldering  on  a 
narrow  strip  of  plate  or  half-round  wire  as  indicated  at  a,  a,  Fig. 
99. 

A  more  perfect  adaptation  of  the  plate  to  the  ridge  may  be  obtained 
by  the  use  of  a  double  instead  of  a  single  plate,  in  which  case  a  thin 
plate,  not  exceeding  No.  30  of  the  gage,  should  be  swaged  to  the 
form  of  the  ridge  in  the  first  instance,  and  then  a  duplicate  plate, 
swaging  the  two  together  and  uniting  them  to  each  other  with  solder. 
A  plate  of  the  specified  thickness  may  be  very  readily  and  accurately 
conformed  to  any  irregularities  in  the  ridge,  and  when  the  two  are 
united  the  base  will  be  heavier  and  stronger  than  a  single  lamina  of 
the  ordinary  thickness.     Instead,  however,   of   doubling  the  entire 


238  MECHANICAL   DENTISTRY. 

plate,  it  will  be  sufficient,  in  most  cases,  to  adapt  the  second  plate 
only  to  the  lingual  surface  of  the  first,  extending  it  up  from  the 
lower  edge  to  a  point  corresponding  as  nearly  as  possible  with  the 
inner  portions  of  the  base  of  the  teeth  when  the  latter  are  adjusted 
to  the  plate,  that  is,  at  about  the  point  indicated  at  a,  a,  Fig.  99.  A 
moderately  thin  plate  may,  in  this  manner,  be  used  for  the  primary 
base,  while  the  duplicate  band  will  impart  the  requisite  strength  to 
the  plate,  and,  at  the  same  time,  obviate  the  necessity  of  wiring  its 
lingual  border.  In  adopting  either  of  the  last-named  methods,  the 
plates,  after  they  are  united  to  each  other,  should  be  again  swaged 
to  correct  any  change  of  form  incident  to  the  use  of  solder. 

Fig.  99. 


Antagonizing  Model  for  an  Entire  Upper  and  Lower  Denture. 

— The   following  method   is   adopted   in   securing  an   antagonizing 
model  for  complete  dentures  : 

Attach  to  the  ridge  of  each  plate  a  roll  or  strip  of  adhesive  wax 
corresponding  in  width  to  the  length  of  the  teeth  which  will  be 
required  for  each  plate  respectively;  place  the  plates,  with  the  wax 
attached,  in  the  mouth,  and  trim  away  from  the  proximate  edges  of 
the  wax  until  the  two  sections  close  upon  each  other  uniformly 
throughout  the  circle ;  then  cut  away  from  the  labial  surfaces  of  the 
rims  of  wax,  above  and  below,  until  the  proper  fulness  and  required 
contour  of  the  parts  associated  with  the  lips  and  mouth  are  secured. 
The  approximation  of  the  two  jaws,  when  the  finished  substitutes  are 
ultimately  adjusted  to  the  mouth,  will  depend  altogether  upon  the 
aggregate  width  given  to  the  two  sections  of  wax  at  this  stage  of 
the  operation,  and  it  is,  therefore,  important  that  the  "  bite  "  or  clos- 
ure of  the  jaws  secured  at  this  time  should  be  such  as  will  most 


ENTIRE   DENTURES    ATTACHED   TO    SWAGED    PLATE-BASE.         239 

perfectly  fulfil  the  requirements  of  the  case  in  respect  to  the  utility 
and  comfort  of  the  appliance,  and  the  proper  restoration  of  the  nor- 
mal facial  expression. 

Re-posing  the  Features. — If  there  is  any  considerable  change 
produced  in  the  relation  of  the  jaws  habitual  to  them  prior  to  the 
loss  of  the  natural  teeth,  the  Characteristic  expression  of  the  indi- 
vidual will  be  very  much  changed  or  marred ;  an  unnatural  and  re- 
strained action  will  be  imposed  upon  the  muscles  concerned  in  the 
movements  of  the  lower  jaw,  which  will  render  the  use  of  the  appli- 
ances, at  least  temporarily,  if  not  permanently,  uncomfortable  and 
fatiguing,  or  even  painful ;  while  the  utility  of  the  fixtures  may  be 
impaired  or  wholly  destroyed  by  compelling  a  particular  application 
of  forces  in  mastication  inconsistent  with  their  stability  in  the  mouth. 
No  specific  directions,  of  course,  can  be  given  that  will  apply  to  all 
cases,  but  it  may  be  observed  that,  ordinarily,  the  two  sections  of 
wax  should  be  cut  away  from  their  approximating  surfaces  until  the 
jaws  close  sufficiently  to  permit  the  edges  of  the  lips  to  rest  easily 
and  naturally  upon  each  other  when  in  a  relaxed  condition,  or  the 
upper  rim  may  extend  somewhat  below  the  margin  of  the  upper  lip, 
while  the  lower  section  of  wax  is  cut  away  on  a  level  with  the  lower 
lip,  or  a  little  below  it.  Cases  occur,  however,  where  a  less  exposure 
of  the  upper  portion  of  wax,  even  though  quite  narrow,  will  be  re- 
quired ;  as  where  the  alveolar  ridge  is  very  deep,  and  the  lip  covering 
it  either  absolutely  or  relatively  short,  or  where  the  latter  is  retracted, 
exposing,  even  when  in  a  state  of  repose,  a  greater  portion  of  all  of 
the  crowns  of  the  teeth,  and  in  extreme  cases  the  margins  of  the  gum. 
Between  the  latter  extreme  and  an  inordinate  extension  of  the  upper 
lip  below  the  ridge,  all  intermediate  conditions  occur,  and  the  prac- 
titioner, aiming  to  produce  an  agreeable,  harmonious,  and  truthful 
expression  of  all  the  parts,  must  rely  wholly  upon  his  judgment  in 
reference  to  the  necessary  approximation  of  the  jaws,  the  restoration 
of  the  natural  fulness  and  contour  of  the  face,  and  the  relative  length 
to  be  given  to  the  upper  and  lower  teeth. 

The  dentist  needs  to  study  the  face  of  his  patient  as  the  artist 
studies  his  picture,  for  he  displays  his  genius  not  upon  canvas  but 
upon  the  living  features  of  the  face.  He  should  know  the  origin 
and  insertion  of  the  principal  muscles  of  which  the  face  is  formed, 
and  which  ones  he  is  to  raise,  otherwise  he  will  be  liable  to  produce 
distortion   instead    of    restoration.     This    improvement    consists    of 


240 


MECHANICAL   DENTISTRY. 


prominences  made  upon  the  denture  of  such  form  and  size  as  to 
bring  out  each  muscle  or  sunken  portion  of  the  face  to  its  original 
fulness ;  and  when  these  are  rightly  formed,  they  are  not  detected 
by  the  closest  observer  (see  Fig.  ioo).  There  are  four  points  of 
the  face  (of  many  persons)  which  the  mere  insertion  of  the  teeth 
does  not  restore,  viz.,  one  upon  each  side  beneath  the  malar  or  cheek 
bone,  and  also  a  point  upon  each  side  of  the  base  of  the  nose,  in  a 
line  toward  the  front  portion  of  the  malar  bone. 

The  extent  of  this  falling-in  varies  in  different  persons,  accord- 
ing to  their  temperaments.  If  the  lymphatic  temperament  predomi- 
nates, the  change  will  be  slight.     If  nervous  or  sanguine,  it  may  be 


Fig.  ioo. 


very  great.  The  muscles  situated  upon  the  sides  of  the  face,  and 
which  rest  upon  the  molar  or  back  teeth,  are  the  zygomaticus  major, 
masseter,  and  buccinator.  The  loss  of  the  upper  teeth  causes  these 
muscles  to  fall  in.  The  principal  muscles  which  form  the  front  por- 
tion of  the  face  and  lips  are  the  zygomaticus  minor,  levator  labii 
superioris  alseque  nasi,  and  orbicularis  oris. 

These  rest  upon  the  incisor,  cuspid,  and  bicuspid  teeth,  which, 
when  lost,  allow  the  muscles  to  sink  in,  thereby  changing  the  form 
and  expression  of  the  mouth. 

The  insertion  of  the  front  teeth  will,  in  a  great  measure,  bring 
out  the  lips,  but  there  are  two  muscles  in  the  front  portion  of  the 
face  which  cannot,  in  many  cases,  be  thus  restored  to  their  original 
position ;  one  is  the  zygomaticus  minor,  which  arises  from  the  front 
part  of  the  malar  bone,  and  is  inserted  into  the  upper  lip  above  the 
angle  of  the  mouth;  the  other  is  the  levator  muscle,  which  arises 
from  the  nasal  process  and  from  the  edge  of  the  orbit  above  the  in- 


ENTIRE   DENTURES    ATTACHED   TO    SWAGED    PLATE-BASE.  24 1 

fraorbital  foramen.  It  is  inserted  into  the  ala  nasi,  or  wing  of  the 
nose  and  upper  lip. 

The  prominences  before  mentioned,  applied  to  these  four  points 
of  the  face,  beneath  the  muscles  just  described,  bring  out  that  nar- 
rowness and  sunken  expression  about  the  upper  lip  and  cheeks  to 
the  same  breadth  and  fulness  which  they  formerly  displayed.  If 
skill  and  judgment  have  been  exercised  in  building  up  and  forming 
the  wax  bite-pieces  and  is  continued  throughout  the  operation,  the 
result  will  be  highly  pleasing  and  of  practical  utility. 

Projection  of  the  Lower  Jaw. — Patients,  when  requested  to 
close  the  mouth  naturally,  are  very  liable  to  project  the  lower  jaw; 
hence  it  is  well  to  have  them  open  and  close  the  jaws  several  times, 
observing  at  the  same  time  if  the  separate  portions  of  wax  meet  in 
precisely  the  same  manner  at  each  occlusion.  If  the  bite  varies  at 
every  approximation  of  the  jaws,  directions  should  then  be  given  to 
relax  and  abandon  for  the  moment  all  control  over  the  muscles  of 
the  lower  jaw;  the  patient  should  then  be  directed  to  close  lightly 
upon  the  wax  in  the  back  part  of  the  mouth.  The  attention  thus 
being  drawn  in  that  direction,  the  jaw  will  naturally  come  back  and 
close  in  the  normal  position.  The  median  line  should  then  be  drawn 
across  both  plates,  and  a  cross,  or  two  or  three  oblique  lines  made 
on  each  side;  after  this  is  accomplished,  the  patient  should  again  be 
directed  to  open  and  close  the  mouth,  and  note  whether  these  lines 
are  brought  accurately  together;  if  so,  it  is  fair  to  assume  that  the 
bite  is  correct.  We  should  then  have  the  patient  bring  slight 
pressure  upon  them  by  closing  the  jaws  a  little  harder,  when,  if  the 
occluding  surfaces  have  been  previously  passed  over  the  flame,  they 
will  adhere  so  firmly  that  they  may  be  readily  removed  from  the 
mouth  together,  without  displacement.  Or  a  heated  knife-blade 
may  be  passed  between  the  two  sections,  the  melted  wax  temporarily 
uniting  them.  Another  very  convenient  and  secure  method  is  to 
attach  them  together  by  means  of  two  strips  of  metal  bent  in  the 
form  of  a  staple ;  these  may  be  warmed  in  a  spirit-flame,  and  pressed 
into  the  wax,  one  on  each  side — one  end  penetrating  the  upper  rim 
of  wax,  the  other  the  lower. 

The  plates,  attached  to  each  other  as  shown  in  Fig.  101,  may  be 

removed  from  the  mouth,  plaster  mixed  and  poured  into  them  to 

form  temporary  models   for  attachment  in  the  articulator.     When 

the  plaster  is  sufficiently  condensed,  the  line  across  the  wax  in  front 

16 


24- 


MECHANICAL    DENTISTRY. 


should  be  extended  in  a  direct  line  across  the  borders  of  the  plaster 
model  above  and  below,,  as,  in  arranging  the  teeth,  the  wax  will  be 


Fig. 


removed,  and  without  this  precaution  the  mesial  point  of  the  mouth 
may  be  lost. 

Antagonizing  Model  for  an  Entire  Upper  Denture  with  the 
Natural  Teeth  of  the  Lower  Jaw  Remaining. — In  forming  an  an- 
tagonizing model  to  be  used  as  a  guide  in  arranging  and  articulating 
a  full  upper  denture  where  all  or  a  part  of  the  natural  organs  of  the 
inferior  jaw  are  remaining,  a  rim  of  wax  should  first  be  adjusted  to 
the  borders  of  the  plate,  one  or  two  lines  wider  than  the  required 
length  of  the  artificial  teeth.  When  placed  in  the  mouth,  the  exterior 
surface  of  the  wax  draft  should  be  cut  away  or  added  to,  until  the 
proper  fullness  of  the  parts  is  restored.  The  patient  should  then 
close  the  lower  teeth  against  the  wax,  imbedding  them  just  sufficiently 
to  indicate  the  cutting  edges  and  grinding  surfaces.  The  median 
line  of  the  mouth  is  then  indicated  upon  the  wax  and  the  plate  re- 
moved, when  the  two  casts  (the  lower  having  been  previously  secured 
from  a  wax  or  modeling  compound  impression)  should  be  secured  in 
the  articulator  as  illustrated  in  Fig.  102. 

Articulators. — Various  articulators  have  been  devised.  Fig. 
103  illustrates  one  of  the  simpler  forms,  while  a  very  ingenious  and 
novel  device  has  been  brought  to  the  notice  of  the  profession  by 
Dr.  W.  G.  A.  Bonwill,  to  which  we  give  considerable  space.  The 
inventor  has  characterized  it  as  the  "  Anatomical  Articulator,"  and 
describes  it  as  follows : 


ENTIRE    DENTURES    ATTACHED   TO    SWAGED   PLATE-BASE. 


243 


"  It  is  modeled  on  the  same  geometrical  system  as  the  human  jaw. 

"  I  found  by  measurement  that  the  average  width  of  the  lower 
jaw  from  center  to  center  of  each  condyle  was  four  inches,  and  from 
the  same  center  of  each  condyloid  process  to  the  median  line  of  the 
lower  jaw.  where  the  cutting  edges  of  the  lower  incisors  meet,  was 
also  four  inches,  making  of  the  human  jaw  an  equilateral  triangle. 
This  holds  good  in  all  jaws,  and  the  difference  of  Y\  of  an  inch  in  this 

Fig.  102. 


radius  of  a  circle  of  four  inches  would  make  but  little  practical  dif- 
ference as  to  the  results. 

"  This  beautiful  law  enables  us  to  have  the  fullest  benefit  of  mas- 
tication at  the  least  expense  of  power  and  motion  in  the  arc  of  the 
circle  of  four  inches  as  a  radius. 

"  This  being  an  absolute  law,  I  have  so  made  this  articulator,  and 
the  cast  of  every  case  is  set  therein  with  the  median  line  at  the  lower 
centrals  just  four  inches,  by  the  dividers,  from  each  condyloid  pro- 
cess. If  an  unusually  large  jaw,  then  the  cast  is  put  a  very  little 
distance  further  out. 

"  For  all  full  sets,  the  articulation  is  so  perfect,  as  made  in  this,  in 
the  laboratory,  as  to  need  but  a  trifling  touch  in  fitting:  in  the  mouth. 


244 


MECHANICAL    DENTISTRY. 


"  I  found  that  there  is  a  further  positive  law  in  the  mechanism  of 
the  human  jaw  that  should  be  regarded  in  every  substitute  made 
therefor,  and  that  is,  just  in  proportion  to  the  depth  of  overbite  of 
the  centrals,  there  is  a  curvature  from  the  mesial  surface  of  the  first 
molars  back,  through  the  other  molars,  up  the  ramus.  That  this 
curvature  upward  and  backward  at  the  ramus  is  due  solely  to  the 
depth  of  closure  of  the  upper  over  the  lower  jaw.  That  where  there 
is  occlusion  or  closing  of  the  cutting  surfaces  of  the  incisors  directly 

Fig.   103. 


upon  each  other,  then  a  straight  line,  directly  backward,  is  the  conse- 
quence. If  curved  at  the  ramus,  in  such  a  case  no  lateral  or  forward 
movement  of  the  lower  jaw  could  occur — only  the  up  and  down. 

"  When  there  is  l/g  of  an  inch  depth-  of  bite,  then,  as  you  go  back 
to  the  center  of  motion — the  condyloid  processes — the  cusps  in  the 
bicuspids  and  molars  grow  less  deep,  and  the  curvature  at  the  ramus 
is  ]4>,  of  an  inch  out  of  line. 

"  When  there  is  an  overbite  of  J/x  of  an  inch,  then,  in  opening 
the  lower  jaw  and  carrying  it  forward  to  use  the  incisors  for  cutting, 
the  back  teeth  of  the  lower  jaw  are  brought  forward;  and  as  the 
second  molar  is  higher  out  of  line  than  the  first  molar,  it  comes  in 
contact  with  the  distal  surface  of  .the  first  superior  molar,  which 
begins  just  here  to  curve  upward,  and  is  the  highest  out  of  line  in 


ENTIRE    DENTURES    ATTACHED   TO    SWAGED    PLATE-BASE. 


245 


the  superior  jaw,  and  they  meet  at  the  same  time  that  the  incisors 
do.  And  the  same  law  holds  good  when  the  lower  jaw  is  turned  to 
the  right  or  left;  the  molars  are  brought  in  contact  to  equalize  the 
force  which  would  be  brought  upon  the  incisors  only.  Besides,  the 
recognizing  of  this  law  enables  the  cusps  or  palatal  and  lingual  sides 
of  the  molars  of  both  jaws  to  be  utilized  in  every  position  the  lower 
jaw  may  take  in  mastication.  Upon  this  plan  I  make  all  my  arti- 
ficial dentures,  most  of  their  articulating  surfaces  being  utilized  at 
every  position  of  the  lower  jaw.     Any  human  jaw  will  show  this 

Fig.  104. 


system,  which,  by  this  system,  can  be  made  just  as  complete,  and 
more  so  in  many  cases,  than. the  normal,  or  such  as  is  found  in  ad- 
vanced civilization. 

"  When  a  set  of  teeth  is  commenced  in  this  articulator  with  the 
upper  overbiting  the  lower  )/%  of  an  inch,  as  you  set  each  tooth  back- 
ward toward  the  condyloid  processes  they  will  assume  the  exact 
angle  and  depth  of  cusps,  as  well  as  the  curvature  at  the  ramus,  as 
found  in  nature.  If  both  jaws  are  in  direct  opposition  at  the  in- 
cisors, then  all  of  the  teeth  must  of  necessity  be  on  a  perfect  plane, 
or  but  one  would  touch  when  in  lateral  position. 

"  With  this  one  base,  which  Fig.  104  shows,  there  is  a  separate 
bow  to  each  part  of  base,  one  for  upper  and  one  for  lower  jaw,  which 
can  be  removed  as  soon  as  the  plaster  in  one  case  is  allowed  to  harden 
on  the  rim.     This  can  be  marked  and  laid  away  for  a  vear  if  neces- 


246  MECHANICAL    DENTISTRY. 

sary,  and  then  articulated.  A  pair  of  bo.ws  can  be  used  for  as  many 
separate  cases,  while  only  one  base  is  required,  which  should  be  made 
absolutely  and  geometrically  exact— approximately  so. 

"  The  set  screw  in  the  center  is  to  hold  the  jaw  or  casts  apart  after 
the  proper  distance  has  been  secured  in  taking-  the  bite.  Or  this 
may  be  regulated  on  the  bite  in  wax,  which,  before  it  is  taken  off 
the  base-plate,  has  the  exact  height  marked  by  a  pair  of  dividers 
on  the  plaster  at  the  median  line,  measuring  from  the  cutting  edge 
of  wax,  and  then,  when  the  first  central  or  block  is  set,  there  is  no 
longer  any  call  for  a  prop  to  keep  open  the  jaws  of  the  articulator. 
When  this  height  is  taken  with  the  dividers,  it  is  marked  on  the 
top  of  each  cast  for  future  reference.  The  dividers  make  each  cast 
exact  without  a  scale  for  measurement. 

"  Articulate  the  upper  set  first,  and  retain  on  the  lower  base  the 
wax  for  length  and  fulness.  When  the  upper  are  all  on,  then  the 
lower  incisors  are  gaged  as  to  the  height  or  length  by  the  dividers 
while  the  wax  is  still  on  the  base-plate  and  taken  from  the  height 
marked  on  the  lower  cast  for  reference. 

"  M ake  the  lateral  movement  as  soon  as  the  first  tooth  or  block 
is  in  position  where  the  case  is  an  upper  one  with  a  good  lower  jaw 
of  natural  teeth. 

"  When  a  full  set,  the  upper  are  first  ground  on  and  shaped  so  as 
to  meet  the  intended  overbite,  and  when  the  lower  set  are  ground  on, 
the  upper  can  be  changed  to  suit  the  lower,  so  as  to  allow  the  whole 
of  every  cusp  to  touch  at  nearly  every  lateral  movement  of  jaw. 

"  When  the  plaster  case  is  to  be  set  in  the  articulator,  it  must  be 
done  with  the  dividers  set  just  four  inches,  with  one  point  at  the 
median  line  as  formed  by  the  lower  incisors,  and  the  other  carried 
over  to  each  condyloid  process  as  marked  on  the  articulator.  This 
makes  the  center  of  jaw  equidistant  from  the  condyles.  The  study 
of  this  principle  will  make  one  fully  realize  the  beautiful  workings 
of  Divinity,  which  is  only  governed  by  positive  law  in  every  depart- 
ment of  the  universe.  With  this  plan  understood,  one  will  never 
again  attempt  to  articulate  a  set  of  teeth  on  the  unwritten  law,  as 
now  universally  made  and  recognized  by  every  dentist  in  the  land. 

"  Until  this  system  is  taught  in  the  schools  and  by  private  prac- 
titioners, no  truly  artistic  and  fully  natural  set  of  teeth  can  ever  be 
made,  for  we  have  been  without  law  in  this  department.  To  de- 
scribe it   is  not   enough.     Jt  must  be  seen   and   demonstrated,  one 


ENTIRE   DENTURES   ATTACHED   TO    SWAGED   PLATE-BASE.         247 

tooth  at  a  time,  until  the  whole  set  is  made.  Only  in  this  way  can 
it  be  understood. 

"  The  construction  of  this  articulator  is  very  simple.  It  is  made 
of  brass  wire  (y%  of  an  inch  in  diameter),  and  brass  tubing  to  allow 
the  size  of  wire  to  fit  closely,  and  move  freely  therein  when  drawn 
out  or  pushed  up.  The  spiral  spring  on  either  condyle  allows  of 
easy  lateral  motion  to  the  lower  part,  and  from  exactly  the  same 
standpoint  as  in  nature;  that  is,  one  of  the  lower  condyles  moves 
forward  in  the  glenoid  cavity  while  the  other  remains  still.  Every 
part  of  it  is  rigid  except  the  movement  at  the  condyles,  and  the 
joints  or  bows  are  only  temporarily  so.  There  is  also  an  up-and- 
down  motion  made  at  the  condyles  by  raising  the  bow  up  or  down. 

"  No  case,  when  once  fixed  in  it,  can  become  disarranged.  If  the 
bite  in  the  wax  is  not  correct,  no  articulator  can  make  it  so.  You 
must  go  back  again  to  the  mouth  and  retake  it,  which  is  easily  done 
at  first  by  asking  the  patient  to  swallow,  when  the  jaws  will  auto- 
matically close  and  assume  their  normal  position.  If  now  correct, 
there  is  never  any  necessity  for  a  screw  to  change  it  when  once  in 
this  articulator. 

"  There  can  be  no  excuse  for  failure  or  inartistic  work  when  this 
instrument  is  once  understood  and  the  law  controlling  the  human 
jaw.  As  we  may  forever  have  to  resort  to  artificial  dentures,  we 
should  demand  of  the  colleges  that  such  an  instrument  be  used,  and 
it  alone,  as  furnishing  the  only  hope  now  offered  of  an  approach  to 
high-toned,  artistic,  mechanical  dentistry.  Until  we  can  be  taught 
to  appreciate  that  law  is  the  governor  of  the  universe,  and  applicable 
in  every  branch  of  dentistry,  we  are  false  men,  and  will  set  '  false 
teeth,'  and  never  realize  our  high  destiny." 

Grinding  and  Adjusting  Single  Gum  Teeth. — In  arranging  or 
adjusting  single  gum  teeth  to  the  plate  in  those  cases  where  the 
changes  in  the  form  of  the  alveolar  ridge,  consequent  on  absorption, 
are  completed,  the  portions  applied  to  the  base  should  be  ground 
away  sufficiently  to  restore  the  required  fulness  of  the  parts  and  to 
give  proper  length  and  inclination  to  the  teeth.  The  coaptation  of 
the  ground  surfaces  to  the  base  should  be  accurate  enough  to  exclude 
perfectly  particles  of  food,  and  to  furnish  such  a  basis  to  each  tooth 
as  will  provide  most  effectually  against  fracture  when  acted  upon  by 
the  forces  applied  to  them  in  the  mouth.  The  gum  extremities  of 
the  teeth  should  also  be  accurately  united  to  each  other  laterally  by 


248  MECHANICAL   DENTISTRY. 

grinding  carefully  from  their  proximate  edges  until  the  joints  or 
seams  will  be  rendered  incapable  of  ready  detection  in  the  mouth, 
care  being  taken  that  this  coaptation  of  the  adjoining  surfaces  is  uni- 
form, for  if  confined  to  the  outer  edge  alone,  portions  of  the  gum 
enamel  may  be  broken  away  in  the  process  of  soldering. 

Arranging  for  Temporary  Plates. — In  the  construction  of  sub- 
stitutes designed  to  fulfil  only  a  temporary  purpose,  and  where  the 
alveolar  processes  remain  in  a  great  measure  unabsorbed,  and  plain 
teeth  (those  representing  but  the  crowns  of  the  natural  organs)  'are 
used,  but  little  skill  will  ordinarily  be  required  in  adjusting  and  fitting 
them  to  the  base.  If  the  ridge  in  front  is  prominent  and  but  inade- 
quately concealed  by  the  lip,  as  where  the  teeth  have  been  but  re- 
cently extracted,  all  those  portions  of  the  border  of  the  plate  in 
front,  anterior  to  the  first  or  second  bicuspid  on  each  side,  may  be 
cut  away  on  a  line  a  little  within  the  required  circle  of  the  anterior 
teeth  and  scalloped,  permitting  the  anterior  cervical  portions  of  the 
artificial  incisors  and  cuspids,  and,  in  some  cases,  the  anterior  bicus- 
pids, to  overlap  the  edge  of  the  plate  and  rest  directly  and  firmly 
upon  the  gum  in  front.  This  abridgment  of  the  plate  is  shown  in 
Figs.  94,  95,  page  231,  and  will  not,  ordinarily,  materially  affect  the 
adhesion  or  stability  of  the  substitute. 

There  are  cases  of  a  mixed  character  that  render  it  more  difficult 
to  effect  a  harmonious  and  symmetrical  arrangement  of  the  teeth, 
as  where  a  limited  number  of  the  natural  teeth  at  intervals  have  been 
long  absent,  and  the  excavations  in  the  ridge  consequent  on  absorp- 
tion alternate  with  other  points  upon  the  ridge  in  a  comparatively 
unchanged  condition.  To  give  uniformity  to  the  denture  by  restor- 
ing perfectly  the  required  circle  of  the  arch  in  such  cases  will  neces- 
sitate the  employment  of  plain  and  single  gum  teeth  conjointly. 
Whenever  necessary,  those  portions  of  the  base  occupied  by  the  plate 
teeth  may  be  cut  away  in  such  a  manner  as  to  permit  the  latter  to  be 
adjusted  directly  to  the  unabsorbed  gum  as  before  described. 

Arranging  the  Teeth  for  a  Full  Upper  and  Lower  Denture. — 
In  the  process  of  grinding  the  teeth  to  the  base,  above  and  below,  the 
operator  should  commence  by  first  arranging  the  superior  central 
incisors,  and  then  the  lower,  and  so,  passing  back  from  tooth  to 
tooth,  grind  and  adjust  an  upper  and  lower  tooth  alternately,  keep- 
ing the  upper  ones  in  advance  of  those  of  the  lower  jaw.  The  cen- 
tral incisors  above  should  be  placed  parallel  with  each  other,  but  the 


ENTIRE   DENTURES   ATTACHED   TO    SWAGED   PLATE-BASE.  249 

cutting  edges  of  the  laterals  and  the  points  of  the  cuspids  should 
incline  slightly  toward  the  median  line  of  the  mouth.  In  arrang- 
ing the  teeth  of  the  upper  jaw,  the  anterior  six  may  be  made  to 
describe,  with  more  or  less  exactness,  the  segment  of  a  circle,  but 
a  somewhat  abrupt  angle  may  be 
given  to  the  arch  on  each  side  by  FlG-  I05- 

placing  the  first  bicuspid  within  the 
circle  in  such  a  way  that,  when 
standing  directly  in  front  of  the 
patient  and  looking  into  the  mouth, 
only  a  narrow  line  of  the  exterior 
face  of  the  crowns  of  these  teeth 
will  be  seen,  while  the  remaining 
teeth  posterior  to  them  should  be 
arranged  nearly  on  a  straight  line, 
diverging  as   they  pass  backward. 

When  arranged  in  the  manner  described,  the  peripheral  outline  of 
the  arch  will  exhibit  somewhat  the  form  presented  in  the  diagram 
(Fig.  105). 

In  regard  to  the  practical  efficiency  of  an  upper  denture  retained 
in  the  mouth  by  atmospheric  pressure  or  adhesion,  it  is  important 
that  the  teeth  engaged  in  the  comminution  of  food,  as  the  bicuspids 
and  molars,  should  occupy  a  position  directly  over  the  central  line 
of  the  ridge,  and  should  either  be  arranged  vertically  or  with  a 
slight  inclination  toward  the  center  of  the  mouth.  The  liability  to 
displacement  of  the  substitute  in  mastication  will  thus  be  greatly 
diminished,  whereas,  if  placed  outside  of  the  line  indicated,  and 
especially  with  a  diverging  inclination,  the  stability  of  the  appliance 
will  be  endangered  and  the  functions  of  mastication  impeded,  not- 
withstanding other  conditions  necessary  to  complete  success  have 
been  fully  secured.  In  arranging  the  upper  and  posterior  teeth  as 
described,  it  will  sometimes  be  necessary  to  give  to  the  opposing 
under  teeth  a  decided  inward  inclination  in  order  to  effect  a  satis- 
factory antagonism  of  the  teeth ;  and  cases  occur  where  a  practical 
articulation  cannot  be  secured  without  departing  in  some  degree 
from  the  arrangement  of  the  upper  teeth  spoken  of, — as  where  a 
great  disparity  exists  between  the  posterior  transverse  diameters  of 
the  two  jaws,  a  medium-sized,  or  even  small  arch  above  being  asso- 
ciated with  an  expanded  ridge  below. 


25O  MECHANICAL   DENTISTRY. 

In  articulating  the  upper  and  lower  teeth,  the  normal  occlusion 
of  the  natural  organs  should  be  imitated  as  nearly  as  the  other  essen- 
tial requirements  of  the  case  .will  admit.  Hence  the  upper  front 
teeth,  describing  the  segment  of  a  larger  circle  than  the  correspond- 
ing teeth  of  the  lower  jaw,  will  project  beyond  and  overlap  slightly 
the  cutting  edges  of  the  latter ;  and  having  a  greater  width  of  crown, 
they  will  extend  latterly  beyond  the  opposing  teeth,  covering  one- 
third  of  the  crowns  of  those  next  adjoining,  so  that  when  the  cus- 
pids of  the  upper  jaw  are  reached,  they  will  close  between  the" lower 
cuspids  and  first  bicuspids;  and,  passing  back,  the  anterior  superior 
bicuspids  between  the  first  and  second  bicuspids  below ;  the  posterior 
bicuspids  above,  between  the  second  inferior  bicuspids  and  anterior 
molars ;  the  first  superior  molars  between  the  first  and  second  molars 
below ;  while  the  anterior  half  of  the  posterior  molars  above  will 
close  upon  the  posterior  half  of  the  inferior  second  molars,  the  re- 
maining posterior  half  of  the  second  molars  above  extending  poste- 
riorly beyond  those  of  the  lower  jaw.  The  outer  cusps  of  the  supe- 
rior bicuspids  and  molars  will  overlap  those  of  the  inferior  teeth; 
while  the  inner  cusps  of  the  teeth  of  the  superior  jaw  will  pass  into 
the  depressions  in  the  lower  teeth  formed  by  the  internal  and  exter- 
nal cusps,  and  the  external  cusps  of  the  inferior  teeth  will,  in  like 
manner,  be  received  into  the  corresponding  excavations  of  the  upper 
teeth.  An  abnormal  relation  of  the  jaws,  as  where  undue  projec- 
tion, absolutely  or  relatively,  of  either  maxilla  exists,  or  where  the 
lower  jaw  closes  on  one  side  or  other  of  the  upper,  will  frequently 
compel  a  departure  from  the  ordinary  arrangement  of  the  artificial 
organs,  the  extent  of  which  must  be  determined  by  the  necessities 
of  each  individual  case. 

In  selecting  teeth  for  a  full  upper  denture  in  those  cases  where 
natural  organs  are  remaining  below,  or  vice  versa,  the  color,  size, 
and  form  of  the  latter  will  serve  as  a  guide  in  the  choice  of  teeth 
appropriate  for  the  opposite  jaw.  In  fitting  and  arranging  the 
teeth  upon  the  base,  and  in  antagonizing  them  with  the  opposing 
natural  teeth,  the  same  general  principles  apply  as  those  already 
adverted  to  in  connection  with  full  upper  and  lower  dentures. 

Having  adjusted  the  teeth  to  the  base,  they  should  be  placed  in 
the  mouth  before  uniting  them  permanently  to  the  plate,  to  detect 
and  remedy  any  error  of  arrangement  cither  in  respect  to  prominence, 
position,  inclination,  length,  or  antagonism. 


ENTIRE   DENTURES    ATTACHED   TO    SWAGED    PLATE-BASE.  25 1 

Forming  a  Rim  to  the  Plate. — If  the  case  is  one  where  single 
gum  or  block  teeth  are  employed,  and  it  is  intended  to  form  a  socket 
or  groove  upon  the  borders  of  the  plate  for  the  reception  of  the  plate 
extremities  of  the  teeth,  the  rim  forming  the  groove  should  be  fitted 
and  soldered  to  the  base  before  investing  the  piece  in  plaster.  If  the 
alveolar  ridge  above  is  shallow,  and  but  imperfectly  concealed  by  the 
lip,  a  rim  to  the  plate  will  be  inadmissible,  as  when  the  mouth  is 
opened  and  the  lip  retracted,  as  in  laughing,  the  metallic  band  will 
he  exposed  to  view.  A  rim  may  be  fitted  and  attached  to  the  base 
in  either  of  the  following  ways : 

1.  A  strip  of  plate  from  one  to  two  lines  in  width  is  adjusted  to 
the  plate,  with  one  edge  resting  on  the  uncovered  border  of  the  plate, 
close  to  the  gum  extremities  of  the  teeth,  and  the  other  overlapping 
and  embracing  the  latter.  The  rim  may  be  more  conveniently  ad- 
justed by  employing  two  pieces,  extending  from  each  heel  of  the 
plate  and  uniting  in  front. 

2.  A  half-round  wire  with  the  edge  beveled  where  it  joins  the 
ends  of  the  teeth,  forming  a  narrow  groove,  may,  in  like  manner, 
be  fitted  to  the  plate,  furnishing  a  shallow  bed  for  the  gum  extrem- 
ities of  the  teeth.  Or  a  narrow  strip  of  plate,  about  the  thickness  of 
heavy  clasp  material,  niay  be  substituted  for  the  half-round  wire. 
In  either  case,  the  better  plan  is  first  to  trace  the  outlines  of  the 
gum  portions  of  the  teeth  upon  the  plate  with  a  sharp  instrument; 
remove  the  wax  and  teeth  from  the  plate;  draw  another  line  a  little 
within  the  first  all  round,  and  solder  the  rim  to  the  line  last  drawn ; 
remove  the  teeth  from  the  wax,  and  readjust  the  latter  in. its  proper 
place  upon  the  plate;  then  fit  each  tooth  separately  to  the  rim  by 
grinding  away  sufficiently  from  the  end  of  the  tooth  to  effect  an 
accurate  adjustment  of  it  to  the  socket.  The  ends  of  the  teeth  may 
be  ground  away  to  the  rim  until  the  platinum  pins  freely  reenter 
the  rivet-holes  in  the  wax,  thus  restoring  them  to  their  proper  posi- 
tion in  relation  to  the  base. 

3.  Another  method  of  forming  a  rim  consists  in  swaging  a  strip 
•of  plate  accurately  to  the  form  of  the  parts  to  which  it  is  applied. 
An  impression  in  wax  or  plaster  is  first  taken  of  the  gum  surfaces 
of  the  teeth  and  exposed  border  of  the  plate;  but  as  it  will  be  im- 
possible to  detach  either  wax  or  plaster  in  perfect  condition  when 
encircling  the  entire  arch,  or  to  swage  perfectly  with  a  die  so  unfa- 
vorably formed  for  stamping,  separate  impressions  of  the  two  lateral 


252  MECHANICAL    DENTISTRY. 

halves  of  the  piece  should  be  taken  from  these  plaster  models,  and 
from  the  latter,  dies  and  counters  produced ; — with  these,  two  strips 
of  plate  of  sufficient  width  are  swaged,  each  extending  from  the  heel 
of  the  plate  to  a  little  beyond  the  median  line  in  front,  overlapping 
slightly  at  the  latter  point.  The  portions  of  the  swaged  strips 
embracing  the  plate  ends  of  the  teeth  are  then  trimmed  to  the  proper 
width,  and  scalloped,  if  desired,  in  correspondence  with  the  festoons 
of  the  artificial  gums.  In  whatever  way  the  rim  is  formed,  when 
it  has  been  fitted  to  the  plate  and  teeth  it  may  be  held  temporarily 
in  place  with  clamps  (such  as  are  shown  in  soldering  air-chamber 
in  plate,  page  201)  adjusted  at  two  or  three  points  around  the  plate 
and  then  transferred  to  a  piece  of  charcoal,  or  soldering  block,  and 
secured  by  first  tacking  it  at  two  or  three  points  with  solder.  The 
groove  may  then  be  filled  with  whiting,  mixed  with  water  or  alco- 
hol to  prevent  the  solder  from  flowing  in  and  filling  it  up ;  after 
which  small  pieces  of  solder  are  placed  along  the  line  of  union  next 
the  edge  of  the  plate,  and  the  rim  permanently  united  throughout 
with  the  blowpipe ;  after  which  the  wax  and  teeth  are  reapplied  to- 
the  plate. 

Constructing  and  Attaching  Spiral  Springs. — The  success 
which  has  been  attained  in  the  use  of  atmospheric  pressure  and  ad- 
hesive plates  has  almost  entirely  superseded  the  necessity  of  employ- 
ing spiral  springs  as  means  of  support ;  nor  should  the  latter  be 
resorted  to  except  under  circumstances  that  preclude  the  use  of  the 
former,  as  in  case  of  cleft  palate,  for  instance.  When  applied,  they 
should  be  attached  to  the  base  on  each  side  between  the  posterior 
bicuspid  and  first  molar  below,  and  opposite  the  posterior  bicuspid 
above.  To  the  border  of  the  plate  near  the  base  of  the  teeth  a  nar- 
row strip  of  plate  is  soldered,  extending  up  and  lying  closely  against 
the  side  of  the  latter,  to  the  end  of  which,  near  the  grinding  sur- 
faces of  the  teeth,  is  adjusted  a  small,  circular  cap  of  gold  connected 
with  the  standard  by  a  small  wire  on  which  the  looped  extremity 
of  the  spring  plays.  To  each  end  of  the  spring  is  attached  a  gold 
swivel,  one  end  to  enter  the  hollow  in  the  wire,  the  other  attached 
to  the  plate,  either  by  soldering  or  vulcanizing  as  the  case  may  be. 
The  appliance  is  shown  in  Fig.  106.  Figs.  107  and  108  exhibit  the 
application  of  springs  to  an  upper  and  lower  denture.  In  this  in- 
stance plain  teeth  with  rubber  attachment  arc  shown,  but  they  may 
be  readily  attached  to  any  form  of  teeth  or  plate. 


ENTIRE   DENTURES    ATTACHED   TO    SWAGED    PLATE-BASE. 


253 


Investing. — The  plate,  with  the  wax  and  teeth  in  place,  is  next 
incased  in  a  mixture  of  plaster,  preparatory  to  backing  the  teeth 
and  uniting  them  with  solder  to  the  base.  For  this  purpose  plaster 
and  sand  may  be  employed,  using  as  little  of  the  former  as  will  serve 


Fig.  106. 


to  hold  the  investment  together  during  the  subsequent  manipula- 
tions. Asbestos  may  be  added,  and  is  a  useful  ingredient.  Burnt 
plaster,  or  that  which  has  been  previously  used  for  investing,  may 
be  substituted  for  the  sand  and  asbestos,  adding  a  sufficient  quantity 


Fig.  108. 


of  unused  plaster  to  effect  consolidation.  Either  of  the  combina- 
tions mentioned  will  suffer  but  little  change  in  the  fire  if  properly 
managed.  It  is  customary  to  incase  the  piece  in  the  plaster  mix- 
ture to  the  depth  of  from  ]/2  to  }i  of  an  inch,  leaving  only  the  lingual 
surfaces  of  the  plate  and  teeth  uncovered. 


;54 


MECHANICAL    DENTISTRY, 


Warping  or  Springing. — However  comparatively  free  from 
change  of  form  the  best  combinations  of  plaster  may  be,  yet  some 
slight  contraction  of  the  body  of  the  investment  doubtless  ensues 
on  the  application  of  heat,  and  it  is  probable  that  so  large  and  re- 
sistant a  mass  must  tend,  in  some  degree,  to  produce  deformity  of 
the  plate  in  soldering;  for,  as  the  investment  contracts  and  the  plate 
at  the  same  time  expands  when  heated,  a  change  in  the  form  of  the 
latter  must  occur  whenever  the  force  exerted  by  the  shrinking  plas- 
ter exceeds  the  expansive  force  of  the  metal ;  and  when  the  peculiar 
form  of  the  upper  plate  is  considered,  we  can  readily  conceive  how 
a  slight  contraction  of  the  plaster  of  the  thickness  mentioned  may 
"  warp  "  or  "  spring  "  the  plate  when  its  uniform  linear  expansion 
and  contraction  is  so  effectively  opposed.  The  change  in  the  form 
of  the  base  from  this  cause  will,  according  to  the  writer's  observa- 
tions, be  found,  in  an  upper  plate,  to  exist  on  each  side  of  the  slop- 
ing walls  of  the  palate,  embracing  the  posterior  half  or  two-thirds 
of  the  plate  at  these  two  points — the  change  manifesting  itself  in  an 
inward  displacement  of  the  lateral  walls  of  the  plate  midway  between 
the  summit  of  the  palatal  arch  and  the  most  depending  portion  of 
the  ridge.  We  would  suggest  in  explanation  of  this  result  that,  as 
the  plaster  contracts  with  sufficient  force  to  carry  the  plate  with  it, 
the  sides  of  the  latter  are  approximated,  while  the  palatal  portion  is 
at  the  same  time  lifted  up.  Now  it  seems  plain,  that  inasmuch  as  the 
portions  of  plate  overlapping  the  ridge  are  incased  in  and  embraced 
by  the  plaster,  and  as  the  palatal  portion  is  arched  in  form  with  its 
convexity  presenting  to  the  plaster,  and  therefore  self-sustaining  in 
respect  to  its  own  peculiar  form,  the  special  configuration  of  these 
parts  cannot  suffer  any  appreciable  change ;  but  as  they  are  forced 
toward  the  common  center  of  the  mass,  their  relation  to  each  other  is 
also  changed,  and  this  changed  relation  must  necessarily  result  in  a 
deformity  of  those  parts  of  the  plate  which  offer  the  least  resistance 
to  the  contractile  force  of  the  plaster.  In  obedience  to  this  neces- 
sity, the  sides  of  the  plate  along  the  sloping  walls  of  the  palate,  which 
from  their  form  are  neither  resistant  nor  self-sustaining  under  press- 
ure, and  whose  inward  displacement  is  unopposed  by  any  counter- 
force,  are  projected  in  toward  the  center  of  the  palatal  excavation 
in  proportion  as  the  borders  and  central  portions  are  approximated 
or  converged  in  the  direction  of  the  center  of  the  piece.  The  prac- 
tical effect  of  this  approximation  of  the  lateral  and  posterior  borders. 


ENTIRE   DENTURES    ATTACHED   TO    SWAGED   PLATE-BASE.  255 

and  internal  displacement  of  the  plate  is  to  make  the  latter  "  bind  " 
upon  the  outer  and  posterior  borders  of  the  alveolar  ridge,  and  to 
throw  the  central  portion  of  the  plate  from  the  roof  of  the  mouth. 

Methods  of  Overcoming  the  Tendency  to  Change  in  Form. — 
To  obviate,  as  far  as  practicable,  any  change  in  the  form  of  the  plate 
which  may  result  from  the  contraction  of  the  plaster  investment, 
various  expedients  have  been  suggested,  but  the  following  will  suf- 
ficiently counteract  the  influence  of  the  plaster  by  permitting  an  un- 
obstructed expansion  and  contraction  of  the  metallic  base.  Take  a 
band  of  tolerably  thick  copper  plate,  as  wide  as  the  plate  and  teeth 
are  deep ;  bend  it  to  the  form  of  the  plate,  but  large  enough  to  leave 
a  space  of  nearly  ^  of  an  inch  between  it  and  the  teeth,  the  ends 
being  united  to  each  other  back  of  the  plate  by  riveting  or  other- 
wise. Holes  are  then  made  in  the  band  at  numerous  points  through- 
out its  extent,  through  which  wire  is  introduced  and  interlaced  on 
the  inside  in  such  a  way  as  to  form  loops,  the  latter  extending  in  to 
within  a  short  distance  of  the  teeth.  The  plaster  is  then  filled  into 
the  space  between  the  band  and  teeth,  even  with  the  cutting  and 
grinding  surfaces  of  the  latter;  the  palatal  surface  of  the  plate  is 
also  covered  with  plaster  and  may  be  connected  with  the  outer  por- 
tion by  a  very  thin  layer  at  the  edge  of  the  plate,  or  the  two  may 
be  entirely  disconnected.  The  expansion  of  copper  being  very  nearly 
that  of  gold,  the  body  of  the  plaster,  when  heat  is  applied,  will  be 
carried  in  advance  of  the  borders  of  the  plate  as  the  latter  expands, 
while  the  thin  portion  of  plaster  at  the  edges  of  the  plate  will  allow 
the  central  portion  of  the  latter  to  expand  with  but  little  or  no  inter- 
ruption. On  cooling,  the  entire  mass  will  contract  and  assume  its 
original  form,  unless  warping  is  induced  by  other  agencies  acting 
independently  of  the  enveloping  plaster,  as  excess  or  unequal  distri- 
bution of  solder,  irregular  heating,  etc. 

It  is  not,  ordinarily,  necessary  to  provide  by  any  special  expedient 
against  warping  of  the  lower  plate,  as  any  slight  change  of  form 
consequent  on  contraction  will  not  materially  affect  its  adaptation  to 
the  lower  jaw — its  only  effect  being  to  impart  to  the  substitute  a 
slight  lateral  play  upon  the  ridge.  The  plaster  on  the  inside  of  the 
lower  piece  may  be  cut  away  to  the  edge  of  the  plate,  while  that 
external  to  the  teeth  should  not  be  added  in  greater  quantities  than 
is  barely  sufficient  to  hold  the  latter  in  place  while  backing  and  sol- 
dering them  to  the  base. 


2^6  MECHANICAL    DENTISTRY. 

Backing  or  Lining  the  Teeth. — The  plate  being  properly  in- 
vested, all  portions  of  the  wax  attached  to  the  inner  surface  of  the 
teeth  and  plate  should  be  thoroughly  removed  with  suitable  instru- 
ments, after- which  stays  or  backings  are  to  be  adjusted  to  the  teeth. 
In  reference  to  the  method  of  forming  and  adjusting  backings,  little 
need  be  added  to  what  has  already  been  said  when  treating  of  par- 
tial dentures.  One  method,  not  there  specified,  consists  in  first 
fitting  to  each  tooth  separately,  in  the  usual  manner,  a  thin  backing 
formed  of  platinum,  which  is  temporarily  fastened  to  the  tooth  by 
splitting  and  spreading  apart  the  ends  of  the  rivets  with  a  small 
chisel-shaped  instrument.  The  teeth  are  then  removed  from  the 
investment  and  partially  imbedded  side  by  side  in  plaster,  the  plati- 
num strips  remaining  uncovered.  The  plaster  and  teeth  may  then 
be  raised  to  a  full  red  heat  with  a  blowpipe  or  by  placing  them  in 
the  furnace.  Small  pieces  of  gold  plate,  of  equal  fineness  with  the 
base,  are  then  placed  upon  the  surfaces  of  the  platinum  backings  and 
thoroughly  fused  with  the  blowpipe  until  they  flow  perfectly  in 
around  the  rivets,  and  uniformly  over  the  surface.  If  sufficient  heat 
is  applied,  the  solder  will  insinuate  itself  between  the  stay  and  tooth, 
and  thus  render  the  coaptation  of  the  two  perfect.  Small  pieces  of 
gold  plate  should  be  added  until  sufficient  thickness  is  imparted. 
The  backings  are  then  trimmed  smoothly,  when  they  may  be  placed 
back  in  the  investment  in  their  appropriate  places.  They  may  then 
be  united  to  each  other  laterally  in  sections  or  continuously,  when 
the  teeth  are  joined  to  each  other  throughout,  a  very  small  quantity 
of  solder  being  sufficient  to  support  them,  provided  it  is  well  diffused 
along  the  joints,  uniting  them  perfectly  at  all  points. 

Soldering  and  Finishing. — The  process  of  preparatory  heating, 
soldering,  pickling,  and  finishing  the  plate  is  the  same  in  all  respects 
as  that  described  when  treating  of  partial  pieces  (see  p.  210),  and 
need  not,  therefore,  be  recapitulated. 

In  the  final  adjustment  of  the  finished  piece  to  the  mouth,  and 
after  any  additional  grinding  of  the  masticating  surfaces  of  the  teeth 
necessary  to  perfect  the  antagonism  has  been  performed,  such  in- 
structions should  be  given  to  the  patient  in  regard  to  the  care  and 
management  of  the  appliances  as  will  best  promote  their  immediate 
and  successful  use.  The  wearer  should  be  impressed  with  the  abso- 
lute necessity  of  early  and  prompt  attention  to  any  injuries  inflicted 
.upon  the  soft  tissues  of  the  mouth  by  the  substitutes,  as  much  future 


ENTIRE   DENTURES    ATTACHED   TO    SWAGED   PLATE-BASE.  257 

trouble  and  annoyance,  if  not  permanent  mutilation  of  the  parts,  may 
result  from  neglect,  but  which  may  be  readily  averted,  in  most  in- 
stances, by  a  timely  removal  of  the  sources  of  injury.  To  obviate, 
in  some  measure,  the  tendency  to  displacement  of  the  base  which 
usually  accompanies  the  first  use  of  artificial  teeth,  and  especially 
the  upper  denture,  the  patient  may  be  directed,  when  dividing  food 
with  the  front  teeth,  to  press  the  substance  backward  and  upward 
against  the  cutting  edges  of  the  superior  incisors  at  the  same  time 
that  the  opposing  teeth  are  closed  upon  each  other,  thus  dividing  com- 
pletely the  substance  seized.  In  reference  to  the  mastication  of  food, 
it  has  been  suggested  to  instruct  the  patient  to  distribute,  by  the 
action  of  the  tongue,  the  portions  of  food  as  equally  as  possible  on 
each  side  of  the  mouth,  in  this  manner  distributing  the  forces  applied, 
and  thereby  lessening  the  chances  of  lateral  displacement  of  the  sub- 
stitute. 


17 


CHAPTER  XXL 

MANUFACTURE  OF  PORCELAIN  TEETH. 

The  perfection  and  completeness  of  results  attained  at  this  day 
in  the  production  of  porcelain  teeth,  approximating  so  nearly  the 
natural  organs  in  all  their  more  obvious,  physical,  and  distinctive 
characteristics  as  to  be  almost,  if  not  quite,  indistinguishable  from 
the  latter  when  applied  in  obedience  to  the  esthetic  requirements 
of  individual  cases,  is  one  of  the  marvels  of  ceramic  art.  Nowhere, 
perhaps,  have  the  conceptions  of  genius  been  embodied  in  porce- 
lain with  more  truthfulness  or  greater  fidelity  to  nature  than  in  the 
exquisite  and  wonderful  imitations  of  the  dental  manufacturing 
laboratory. 

So  amply  and  satisfactorily  has  the  intelligent,  progressive,  and 
well-directed  enterprise  of  manufacturers  provided  for  all  the  ordi- 
nary needs  of  prosthetic  practice  in  the  almost  endless  variety  in 
size,  color,  configuration,  relation,  and  adaptability  of  single  and 
sectional  teeth,  that  the  work  of  hand-carving  is  now  rarely  de- 
manded of  the  general  practitioner,  except  in  extreme  cases  result- 
ing either  from  accident  or  disease.  Thus,  as  aptly  remarked  by 
the  late  Professor  Austen :  "  The  dental  depot  not  only  renders  ser- 
vice by  the  superior  excellence  of  the  surgical  instruments  and 
prosthetic  materials  which  it  supplies,  but  it  directly  benefits  the 
science  and  art  of  dentistry  by  releasing  the  practitioner  from  man- 
ufacturing toil,  and  giving  time  for  the  acquirement  of  increased 
knowledge  and  skill.  Thus,  if  the  time  heretofore  given  to  block- 
making  were  devoted  to  the  study  of  dental  esthetics,  patients  would 
have  the  benefit  of  an  artistic  selection  from  a  far  larger  variety  of 
porcelain  dentures  than  could  otherwise  possibly  be  made." 

As  affording  some  curious  as  well  as  practical  information  in  re- 
gard to  the  composition  and  manufacture  of  porcelain  teeth,  the 
following  descriptions  will  be  found  of  interest: 

Components  of  Dental  Porcelain. — Manufactured  single  and 
sectional  mineral  teeth,  carved  block-teeth,   continuous-gum  mate- 

258 


MANUFACTURE   OF    PORCELAIN    TEETH.  259 

rial,  etc.,  are  composed  of  two  distinct  portions — the  body,  or  base', 
and  enamel.  The  chief  mineral  substances  which  compose  the  body 
are  silex,  feldspar,  and  kaolin.  The  enamel,  both  crown  and  gum, 
consists  principally  of  feldspar. 

The  various  tints  or  shades  are  imparted  to  the  porcelain  by  cer- 
tain metals  in  a  state  of  minute  division,  or  their  oxids.  The  more 
general  properties  of  the  mineral  ingredients  will  be  first  described. 

Silex. — Silex,  silica,  or  silicic  acid,  is  a  white  powder,  inodorous 
and  insipid.  It  forms  the  chief  part  of  many  familiar  mineral  for- 
mations, as  quartz,  rock-crystal,  flint,  agate,  and  most  sands  and 
sandstones,  in  some  of  which  it  occurs  nearly  pure.  Silica,  in  its 
pure  state,  is  insoluble  in  water  or  acids,  and  is  infusible  in  the 
highest  heat  of  the  furnace ;  it  melts,  however,  in  the  flame  of  the 
oxyhydrogen  blowpipe,  passing  into  a  transparent,  colorless  glass. 
Its  specific  gravity  is  2.66 ;  and  it  is  composed  of  silicon,  48.04,  and 
oxygen,  51.96.  Only  the  purest  varieties  of  silex  are  employed  in 
the  manufacture  of  porcelain  teeth.  It  is  prepared  for  use  by  sub- 
jecting it  to  a  white  heat  and  then  plunging  it  into  cold  water,  after 
which  it  is  ground  to  a  very  fine  powder  in  a  mortar. 

Feldspar. — This  mineral  substance  occurs  crystallized  in 
oblique  rhomboidal  prisms,  and  is  a  constant  ingredient  of  granite, 
trachyte,  porphyry,  and  many  of  the  volcanic  rocks.  The  felds- 
pathic  mineral  formations  present  either  a  pearly  or  vitreous  luster, 
and  vary  in  color,  being  red,  green,  gray,  yellow,  brown,  flesh- 
colored,  pure  white,  milky,  transparent,  or  translucent.  Feldspar 
yields  no  water  when  calcined,  melts  at  the  blowpipe  into  a  white 
enamel,  and  is  unaffected  by  acids.  It  is  composed,  according  to 
Rose,  of  silica,  66.75;  alumina,  17.50;  potash,  12;  lime,  125;  oxid 
of  iron,  0.75.  It  is  found  in  various  localities  throughout  the  United 
States,  the  purest  and  whitest  kinds  being  employed  in  the  manu- 
facture of  mineral  teeth.  It  is  prepared  for  use  in  the  same  manner 
as  silex. 

Feldspar,  from  its  ready  fusibility,  serves  to  agglutinate  the  par- 
ticles of  the  more  refractory  ingredients,  silex  and  kaolin ;  and  when 
diffused  throughout  the  mass  imparts  to  the  porcelain  a  semi-trans- 
lucent appearance. 

Kaolin. — Kaolin,  or  decomposed  feldspar,  is  a  fine  white  variety 
of  clay,  and  is  composed  chiefly  of  silica  and  alumina,  the  latter 
being;  the  characteristic  ingredient  of  common  clav.     It  is  found  in 


26o  MECHANICAL   DENTISTRY. 

various  localities  throughout  the  Eastern  States  and  in  parts  of 
Asia  and  Europe.  Kaolin  is  refractory,  or  fire-proof,  but  is  ren- 
dered more  or  less  fusible  by  the  contaminations  of  iron  and  lime 
with  which  it  is  usually  combined.  The  opaque  and  lifeless  appear- 
ance characteristic  of  the  earlier  manufacture  of  mineral  teeth  was 
due  to  the  introduction  of  a  relatively  large  proportion  of  this  clay 
into  the  body  of  the  porcelain.  The  peculiar  translucent  and  lifelike 
expression  which  distinguishes  the  beautiful  imitations  of  the  pres- 
ent day  is  due,  in  great  part,  to  the  comparatively  small  proportion 
of  kaolin  clay,  and  an  increased  amount  of  the  more  fusible  and 
vitreous  component,  feldspar. 

Kaolin  is  prepared  for  use  by  washing  it  in  clean  water;  the 
coarser  particles  having  settled  to  the  bottom,  the  water  holding 
the  finer  ones  in  solution  is  poured  off,  and  when  the  suspended 
clay  is  deposited  at  the  bottom  of  the  vessel,  the  water  is  again 
poured  off,  and  the  remaining  kaolin  dried  in  the  sun. 

Coloring  Materials. — The  following  metals  and  oxids  are  em- 
ployed in  coloring  mineral  teeth :  titanium,  platina  sponge,  and  oxid 
of  gold  being  those  chiefly  used  in  producing  the  more  positive  tints, 
by  combining  which,  in  varying  proportions,  any  desired  shade  or 
color  may  be  obtained : 

METALS    AND    OXIDS.  COLORS    PRODUCED. 

Gold  in  a  state  of  minute  division, Rose  red. 

Oxid    of    gold, Bright  rose  red. 

Platina    sponge, Grayish-blue. 

Oxid  of  titanium, Bright  yellow. 

Purple   of   Cassius, Rose  purple. 

Oxid  of  uranium, Greenish-yellow. 

Oxid  of  manganese, Purple. 

Oxid  of  cobalt, Bright  blue. 

Oxid    of    silver, Lemon  yellow. 

Oxid  of  zinc, Lemon  yellow. 

As  the  preparation  of  most  of  the  above  colors  requires  great 
care  and  a  somewhat  intimate  knowledge  of  chemistry,  and  as  the 
most  delicate  manipulations  arc  necessary  to  secure  accurate  and 
satisfactory  results,  it  is  better  for  the  mechanical  operator  to  pro- 
cure the  coloring  ingredients  already  prepared  from  some  compe- 
tent chemist,  rather  than  attempt  their  production  himself. 

Manufacture  of  Porcelain  Teeth. — The  subjoined  account  of 
the   processes   concerned   in   the   manufacture  of  porcelain   teeth  is 


MANUFACTURE    OF    PORCELAIN    TEETH.  26l 

descriptive  of  those  at  present  employed  by  most  of  our  leading 
manufacturers. 

The  feldspar  is  first  calcined  by  throwing  it  in  large  masses  into 
a  furnace  and  subjecting  it  to  a  red  heat  and  then  plunging  it  into 
water,  which  renders  it  brittle  and  easily  broken  by  the  hammer 
into  small  pieces,  so  that  all  foreign  matters,  such  as  mica  or  iron, 
with  which  it  may  be  mixed,  can  be  separated.  It  is  then  crushed 
between  flint  stones,  and,  when  fine  enough,  is  afterward  ground 
under  water  in  a  mill  in  which  heavy  blocks  of  French  bur-stone 
revolve  upon  a  nether  millstone  of  the  same  material  until  suffi- 
ciently pulverized,  when  it  is  floated  off  and  allowed  to  settle.  After 
this  the  water  is  drawn  off  or  evaporated,  and  the  deposit  of  spar 
dried  and  sifted. 

The  silex  is  subjected  to  the  same  treatment. 

The  kaolin,  already  of  the  desired  consistency  as  found  in  na- 
ture, is  prepared  for  use  by  first  washing  out  impurities,  and  then 
drying. 

The  mineral  ingredients  are  ground  somewhat  coarsely,  but  the 
coloring  materials  are  reduced  to  an  impalpable  powder  by  means 
of  a  mortar  and  pestle  machine  of  great  power. 

When  properly  prepared,  the  several  materials  are  combined  in 
suitable  proportions  to  form  the  body  and  enamels,  and  are  then 
mixed  with  water  and  worked  into  masses  of  the  required  consist- 
ency for  molding.  The  degree  of  plasticity  of  the  body  and  enamel 
pastes  differs  with  the  methods  of  manufacture.  Formerly,  the 
teeth,  when  molded,  were  first  exposed  to  a  heat  just  sufficient  to 
produce  partial  baking  of  the  body,  and  this  was  called  cruising,  or 
bisatiting,  after  which  a  thin  paste  of  enamel  material  was  applied 
with  a  camel's-hair  brush,  and  the  whole  subjected  to  a  second  heat 
for  complete  and  final  fusion.  This  preliminary  process  of  biscuit- 
ing  is  essential  in  carved  block  and  continuous-gum  work,  but  in- 
most of  the  factories  this  partial  baking  is  dispensed  with,  and  the 
body  and  enamel  pastes  of  the  uniform  consistency  of  putty  are 
introduced  into  the  molds,  in  the  first  instance,  properly  distributed, 
and  final  fusion  effected  by  a  single  exposure  to  heat. 

The  molds  are  made  of  brass  and  are  in  two  sections,  one-half 
of  the  tooth  being  represented  on  either  side.  The  exact  form  of 
the  tooth  is  carved  out  with  great  care  and  precision,  and  must  be 
anatomically  correct  ■  and  mechanically  perfect,  .while  the  matrix  is 


262  MECHANICAL   DENTISTRY. 

made  about  one-fifth  larger  than  the  required  size  to  compensate  for 
shrinkage  of  the  materials  in  baking.  Holes  are  drilled  in  each 
half  of  the  mold  to  receive  the  platinum  pins,  and  the  exact  closure 
of  the  two  pieces  of  the  mold  secured  by  guiding  pins. 

The  molds  having  been  previously  oiled,  and  the  platinum  pins — 
which  vary  in  length  and  thickness  to  meet  special  requirements 
— placed  with  small  tweezers  in  the  holes  provided  for  them,  the 
crown  and  gum  enamels  are  first  carefully  laid  in  with  small  steel 
spatulas  in  the  required  quantity  and  position.  The  body  is  then 
added,  in  quantity  exceeding  somewhat  the  capacity  of  the  mold, 
when  the  sections  of  the  mold  are  closed  upon  each  other  and  sub- 
jected to  a  pressure  sufficient  to  insure  compactness  of  the  inclosed 
mass.  When  thoroughly  dried  by  a  slow  heat,  to  which  the  molds 
are  exposed,  the  teeth  are  readily  disengaged  when  the  matrix  is 
separated,  and  will  be  found  at  this  stage  extremely  friable  and 
tender,  requiring  great  care  in  handling  them. 

They  are  then  sent  from  the  molding  to  the  trimmer's  room, 
where,  after  critical  inspection,  all  defective  ones  are  either  repaired 
or  condemned,  all  excess  of  material  cut  smoothly  away,  and  the 
arch  of  the  gum  over  each  tooth  made  true  and  smooth  with  fine 
pointed  instruments.  They  are  then  placed  on  beds  of  coarse  quartz 
sand,  on  fire-clay  trays  or  slides  ready  for  the  furnace. 

Referring  to  this  stage  in  the  process  of  manufacture,  an  intelli- 
gent observer  writes : 

"  Beyond  this  no  tool  can  follow  them.  Imperfections  heretofore 
could  be  repaired,  but  in  the  future,  beyond  the  fire,  the  tooth  is 
either  perfect  or  a  failure  irremediable.  The  furnace  is  an  institu- 
tion entitled  to  respect  for  its  intensity.  In  its  center  is  a  muffle 
of  fire-clay,  entirely  surrounded  by  the  glowing  fuel,  a  charge  of 
half  a  ton's  weight  of  coal,  itself  carefully  bricked  up  before  firing, 
that  no  impurities  of  dust  or  vapor  shall  reach  the  teeth.  Take 
out  the  small,  half-oval  door  of  the  muffle  and  you  will  see  an  inner 
glow  the  eye  shrinks  from  registering,  an  incandescence  that  startles 
you  by  its  fervor.  In  from  fifteen  to  thirty  minutes,  teeth  and  fire- 
clay slide,  glowing  like  the  oven,  are  taken  out  finished.  The  dull 
enamel  has  become  as  glass.  The  lusterless  oxids  have  yielded 
their  color,  and  the  tooth  that  went  in  friable  and  brittle  has  come 
out  adamant.  But  there  is  an  intermediate  skill,  the  acquisition  of 
which  is  one  of  the  marvels  of  the  mechanic  arts.     A  little  too  long 


MANUFACTURE   OF    PORCELAIN    TEETH.  263 

in  that  heat  and  the  teeth  are  ruined,  and  the  evils  of  '  underdone ' 
are  equally  to  be  guarded  against.  It  is  a  trained  judgment,  a  skill 
of  eye  and  handling  that  enables  the  burner  to  lend  success  to  the 
work  of  those  who  have  gone  before  him,  and  at  the  precise  point 
where  a  shade  of  failure  is  utter  ruin." 

The  teeth  are  now  done  and  ready  for  the  wax  cards,  on  which 
they  sfo  to  the  trade. 


CHAPTER  XXII. 

"  CONTINUOUS-GUM  "  DENTURES.* 

The  process  of  uniting  single  mineral  teeth  to  each  other  and  to 
a  metallic  base  by  means  of  a  porcelain  cement  was  attempted  as 
early  as  1820,  by  Delabarre,  of  Paris,  France,  but  with  such  imper- 
fect and  unsatisfactory  results  as  induced  its  early  abandonment. 
At  a  later  period,  Dr.  John  Allen,  a  distinguished  practitioner  of 
dentistry  in  America,  devised  a  method  embracing  original  and 
important  modifications  of  practice,  both  in  the  preparation  and 
combination  of  materials  and  the  modes  of  manipulating  them ;  and 
after  an  extended  series  of  experiments,  commencing  in  1844,  suc- 
ceeded in  obtaining  certain  mineral  compounds  which  vitrified  at  a 
heat  much  below  that  employed  by  Delabarre,  and  the  contraction 
of  which  corresponded  so  nearly  with  that  of  the  platinum  base  to 
which  it  was  applied  that  the  shrinkage  incident  to  baking  conflicted 
in  no  material  degree  with  the  practical  utility  of  the  work  in  the 
mouth. 

In  the  construction  of  dentures  upon  this  principle,  plain  single 
teeth,  made  for  the  purpose,  are  arranged  and  soldered  to  a  plate 
properly  fitted  to  the  mouth,  after  which  different  mineral  com- 
pounds, made  to  represent  the  natural  gum  tissues,  etc.,  are  applied 

*  The  attentive  reader  of  the  early  editions  of  this  work  will  not  fail  to  note 
that  the  statements  involving  the  question  of  priority,  contained  in  the  introduc- 
tory portion  of  the  above  chapter,  are  at  variance  with  those  originally  published. 
A  more  extended  examination  and  careful  analysis  of  the  evidences  as  they  ap- 
pear upon  record — evidences  not  fully  accessible  to  the  author  at  that  time — 
established  beyond  reasonable  doubt  the  just  claims  of  Dr.  Allen  as  the  originator 
of  that  special  and  distinctive  method  here  considered,  by  which  the  attachment 
of  the  teeth  to  the  plate  is  effected  by  direct  fusion  of  the  gum  material.  Dr. 
Hunter's  earliest  and  contemporaneous  experiments  contemplated  simply  a  union 
of  all  the  teeth  by  means  of  a  fusible  cement,  forming  a  single,  continuous  block, 
which  was  afterward  united  to  the  base  by  riveting  or  soldering. 

This  brief  explanation  is  here  introduced  as  an  act  of  simple  justice  to  the  late 
Dr.  Allen,  who  devoted  the  best  energies  of  his  life  to  the  successful  development 
of  a  process  which  stands  unrivaled  in  all  the  chief  requisites  of  an  artificial 
denture. 

264 


"  CONTINUOUS-GUM  "   DENTURES.  265 

to  the  plate  and  teeth  in  a  plastic  state,  then  carved  and  trimmed 
in  proper  form,  and  by  means  of  a  strong  furnace  heat,  these  com- 
pounds, called  the  body  and  the  gum  enamel,  are  fused,  producing 
a  continuous  and  seamless  artificial  gum  and  palate  resembling 
closely  the  natural  structures. 

The  compounds  at  present  employed  in  this  process,  as  well  as 
the  more  fusible  preparations  used  for  repairing  purposes,  are  man- 
ufactured in  quantities  sufficient  to  meet  the  wants  of  the  profes- 
sion, and  may  be  procured  at  all  the  dental  furnishing  houses 
throughout  the  United  States. 

The  intimate  but  later  identification  of  Dr.  W.  M.  Hunter  with  the 
above  process  has  rendered  his  name  familiar  as  one  whose  skill 
and  devotion  to  this  specialty  of  mechanical  practice  has  contributed 
to  its  development  in  a  modified  form.  Dr.  Hunter's  formulas  and 
modes  of  manipulating  his  compounds  will  be  introduced  hereafter. 

Following  Dr.  Hunter's  descriptions,  the  reader  will  find  practical 
and  valuable  instructions  in  this  method  of  substitution,  contributed, 
at  the  solicitation  of  the  author  of  this  work,  by  Professors  S.  P. 
Haskell,  of  Chicago,  111.,  and  George  S.  Field,  of  Detroit,  Mich., 
also  the  late  Dr.  Ambler  Tees,  of  Philadelphia,  Pa.,  whose  long 
experience  and  intimate  familiarity  with  the  most  approved  methods 
of  constructing  continuous-gum  dentures  impart  special  value  to 
the  subject-matter  of  their  communications. 

Before  introducing  an  account  of  Dr.  Allen's  modes  of  procedure, 
we  would  premise  that  it  is  unnecessary  to  repeat  in  this  connection 
what  has  already  been  fully  described  in  regard  to  impressions  of 
the  mouth,  or  the .  manipulations  connected  with  the  formation  of 
plaster  models  and  metallic  swages,  these  processes  being  essentially 
the  same  as  in  the  construction  of  ordinary  gold  work. 

An  ingenious  method  of  attachment  has  been  devised  by  Dr.  C. 
H.  Land,  of  Detroit,  Mich.  The  improvement,  in  its  application 
to  continuous-gum  work,  is  in  the  construction  of  the  teeth,  which 
are  provided  with  three  pins  arranged  transversely  in  the  cervical 
portion  of  the  tooth — one  in  the  center  and  one  upon  either  side  on 
the  posterior  lateral  aspect  of  the  cervix,  the  latter  being  somewhat 
longer  than  the  center  pin.  The  long  pins  at  the  sides  are  so 
arranged  that,  when  the  teeth  are  in  position,  the  lateral  pins  of 
all  the  teeth  will  cross  each  other,  as  shown  in  Fig.  109.  The  pins 
so  crossed,  and  also  the  center  pins,  are  pressed  down  closely  upon 


266  MECHANICAL    DENTISTRY. 

the  plate,  and  the  whole  united  to  each  other  and  to  the  base  by 
flowing  solder  at  the  points  where  they  cross,  and  at  their  line  of 
junction  with  the  base. 

These  teeth  are  designed  more  especially  for  continuous-gum 
work,  but  are  applicable  to  dentures  attached  to  gold  plates  by 
rubber  or  celluloid,  and  may  be  used  also  to  advantage,  in  a  modi- 
fied form,  in  the  use  of  rubber  or  celluloid  alone. 

The  particular  advantages  claimed  for  these  teeth  are,  that  in  their 
use  in  continuous-gum  cases,  equal  or  greater  strength  is  imparted 
to  a  plate  made  much  thinner  than  those  ordinarily  employed,  say 
32  to  33  Stub's  gage,  thus  materially  reducing  the  weight  of  the 
piece,  while  at  the  same  time  they  offer  greater  facility  and  certainty 
in  the  manipulation  of  the  gum  body. 

Fig.   109. 


Dr.  Allen's  Methods. — The  following  descriptions  embrace  the 
methods  and  manipulations  practised  by  the  late  Dr.  John  Allen  in 
the  construction  of  artificial  dentures  with  continuous  gums. 

The  plate  or  base  is  formed  of  platinum,  or  platinum  and  iridium. 
The  plate  being  properly  fitted  to  the  mouth,  and  wax  placed  upon 
it  for  the  bite,  as  in  ordinary  plate  work,  the  teeth  are  arranged 
thereon  with  special  reference  to  the  requirements  of  the  case. 
They  are  then  covered  with  a  thin  coating  of  plaster  mixed  with 
water  to  the  consistency  of  cream.  After  this  has  become  firmly 
set,  another  mixture  of  plaster  and  asbestos  with  water,  somewhat 
thicker  or  more  plastic  than  the  first,  is  placed  round  on  the  out- 
side of  the  previous  covering  and  the  plate.  A  convenient  way  of 
applying  the  second  covering  is  to  turn  the  mixture  out  of  the 
vessel  upon  a  piece  of  tin,  say  four  or  five  inches  square,  thus  form- 


"  CONTINUOUS-GUM  "    DENTURES.  267 

ing  a  cone,  upon  which  the  plate,  .with  the  teeth  upward,  is  pressed 
gently  down  until  within  an  inch  or  less  from  the  tin.  Then  with 
a  spatula  the  mixture  is  brought  up  over  the  teeth,  forming  an  in- 
vestment that  will  not  crack  in  the  process  of  soldering.  Sand 
may  be  used  with  the  plaster  for  this  purpose,  but  asbestos  is  prefer- 
able. 

Attaching  the  Teeth. — When  the  covering  has  become  suffici7 
ently  hard,  the  wax  is  removed,  and  a  rim  of  platinum'  is  then  fitted 
to  the  lingual  side  of  the  teeth,  below  the  pins,  and  to  the  base- 
plate. The  pins  in  the  teeth  are  then  bent  down  upon  the  rim,  and 
soldered  with  pure  gold,  or  a  mixture  of  gold  and  platinum,  at  the 
same  time  the  rim  is  soldered  to  the  plate.  This  rim,  which  forms 
the  lining  for  the  teeth,  is  usually  about  the  thickness  of  the  plate 
upon  which  they  are  set,  say  28  to  30;  but  should  the  case  require 
more  than  ordinary  strength,  a'  double  or  triple  thickness  of  rim 
should  be  used.  This  may  become  necessary  in  cases  where  the 
natural  molar  teeth  are  standing  firmly  in  the  opposite  jaw,  and 
antagonize  with  the  artificial  piece,  or  where  from  any  cause  an 
undue  strain  is  brought  to  bear  upon  the  artificial  teeth.  To  attain 
successful  results,  the  dentist  must  take  into  consideration  all  the 
circumstances  or  conditions  of  each  particular  case,  and  then  exer- 
cise his  best  judgment  in  executing  the  work. 

In  soldering  platinum  with  pure  gold,  flat  surfaces  of  this  metal 
should  be  brought  into  positive  contact,  in  order  to  become  firmly 
united.  Therefore,  in  mounting  teeth  upon  a  plate  of  this  kind,  the 
backing  or  inside  rim  should  be  a  little  wider  than  the  distance 
between  the  pins  in  the  teeth  and  the  plate,  say  from  y%  to  y±  of  an 
inch.  This  extra  width  of  rim  should  be  bent  at  right  angles  along 
the  base  of  the  teeth,  so  as  to  admit  of  being  pressed  down  upon 
the  plate  after  the  rim  is  adjusted  to  the  teeth,  and  the  pins  bent 
down  firmly  upon  it.  In  this  way  flat  surfaces  of  the  rim  and  plate 
are  brought  together  and  soldered.  The  pins  in  the  teeth  are  also 
soldered  to  the  rim  at  the  same  time.  When  the  parts  are  thus 
united,  they  will  remain  so  during  the  subsequent  bakings ;  but  if 
the  edge  of  the  rim  only  is  fitted  to  the  plate  and  soldered  like  gold 
or  silver  work,  the  subsequent  heatings  for  baking  the  body  and 
gum  will  cause  the  gold  to  become  absorbed  in  the  platinum,  and 
leave  the  joints  not  united.  It  is  sometimes  asked,  Why  not  use 
common  eold  solder  for  this   stvle  of  work  ?     To  this  we  would 


268  MECHANICAL    DENTISTRY. 

answer,  because  the  alloy  in  the  solder  will  greatly  injure  the  color 
of  the  gum  enamel  in  baking.  For  instance,  copper  alloy  will  turn 
it  to  a  greenish  shade,  and  silver  will  give  it  a  yellow  tinge.  Al- 
though pure  gold  requires  more  intense  heat  to  melt  it  (being  about 
20000 )  than  ordinary  gold  solder,  yet  when  melted  it  flows  much 
more  freely  than  the  latter.  The  best  way  to  solder  the  teeth  upon 
platinum  plate  is  to  place  small  pieces  of  gold  upon  the  joints  or 
parts  to  be  soldered,  with  wet  ground  borax,  and  then  slowly  intro- 
duce the  piece  with  the  investment  into  a  heated  muffle,  and  bring 
the  whole  mass  up  to  a  red  heat ;  then  withdraw  it  from  the  furnace, 
and  bring  it  quickly  under  the  blowpipe  to  flow  the  gold.  In  this 
way  the  teeth  do  not  become  etched,  as  they  are  liable  to  be  if  the 
soldering  is  done  in  the  furnace. 

The  piece  being  soldered  and  cooled,  the  covering  is  removed 
from  the  teeth,  taking  care  to  preserve  the  base  unbroken  for  the 
plate  to  sit  upon  during  the  subsequent  bakings  of  the  body  and  gum 
enamel. 

Preparing  and  Applying  the  Body. — All  particles  of  plaster  or 
other  foreign  matter  should  be  removed  from  the  teeth  and  plate  by 
thoroughly  washing  and  brushing  them.  It  is  well  to  immerse  the 
piece  for  a  short  time  in  sulphuric  acid,  after  which  rinse  and  brush 
it  well  with  water.  This  done,  a  colorless  mineral  compound,  called 
the  body,  is  applied  in  a  plastic  state  (with  spatulas  or  small  instru- 
ments for  the  purpose)  to  the  teeth  and  plate.  It  is  then  carved 
to  represent  the  gum,  roof,  and  rugse  of  the  mouth,  taking  care  to 
keep  the  crowns  of  the  teeth  well  defined.  Small,  clean  cuts  with 
a  thin  knife-blade  should  then  be  made,  one  between  each  of  the 
teeth.  Commencing  with  the  space  between  the  molars,  the  cuts 
should  be  made,  externally  and  internally,  entirely  through  the  body 
to  the  stay  and  the  plate.  The  object  of  these  separations  is  to 
prevent  movement  on  the  part  of  the  teeth  from  contraction  of  the 
body  in  baking,  compelling  the  material  to  shrink  toward  the  teeth 
and  unite  with  them,  leaving  smooth  and  irregular  openings  where 
the  incisions  were  made,  into  .which  more  material  is  readily  intro- 
duced and  baked. 

First  Baking. — The  piece  is  then  placed  on  the  base  upon  which 
it  was  soldered,  and  set  upon  a  slide  on  the  apron  in  front  of  one 
of  the  upper  muffles  of  the  heated  furnace;  and  every  few  minutes 
it  should  he  moved   forward  into  the  muffle,  say  two  or  three  inches 


CONTINUOUS-GUM        DENTURES. 


269 


each  time,  until  the  piece  shall  have  passed  the  center  of  the  same, 
which  should  be  at  a  red  heat.  It  is  then  withdrawn  and  passed 
into  a  lower  muffle,  where  the  heat  is  greater,  in  which  the  body 


Fig.  iio. 


;soon  becomes  semi-vitrified,  which  is  sufficient  for  the  first  bake. 
It  is  then  taken  out  and,  together  with  the  slide  on  which  it  was 
baked,  placed  in  a  cooling  muffle,  the  mouth  of  which  should  be 


Fig.   hi. 


-closed  to  prevent  the  change  of  temperature  from  being  too  rapid 
.and  causing  the  teeth  to  become  brittle.  Fig.  no  shows  a  case 
.after  the  first  heating.     When  the  piece  is  sufficiently  cool  to  handle, 


2JO  MECHANICAL    DENTISTRY. 

a  second  application  of  body  is  made  for  the  purpose  of  repairing 
any  defects  that  may  have  occurred  in  the  baking;  this  done,  the 
piece  is  again  introduced  as  before  into  the  upper  muffle,  then  into 
the  lower,  allowing  the  second  bake  to  become  a  little  harder  than 
the  first,  but  not  so  much  as  to  appear  glossy.  It  is  then  withdrawn, 
and  cooled  as  described  above. 

Applying  the  Gum  Enamel. — A  flesh-colored  compound  is  then 
applied,  which  is  called  the  gum  enamel.  This  is  also  made  plastic 
with  water,  and  a  thin  coating  is  put  over  the  body  and  closely 
packed  and  carved  around  the  teeth  with  small  instruments  made  for 
the  purpose,  still  taking  care  to  keep  the  crowns  of  the  teeth  clean 
and  well  defined.  Small  camel's-hair  brushes  are  used  wet  with 
water  to  cause  the  gum  enamel,  and  also  the  body,  to  settle  more 
closely  around  the  necks  of  the  teeth ;  other  brushes  are  also  used 
dry  to  remove  all  particles  of  body,  gum,  or  other  substances  from 
the  crowns  of  the  teeth. 

Final  Baking.— After  the  application  of  the  gum  enamel,  the 
piece  is  again  subjected  to  the  heat  of  the  furnace  as  described  for 
baking  the  body,  with  this  difference :  The  heat  should  be  a  little 
greater  than  for  either  of  the  preceding  bakes.  It  should  be  a 
strong,  sharp  heat,  in  order  to  produce  a  smooth,  glossy  appearance, 
which  is  required  for  the  enamel.  These  different  degrees  of  heat 
for  the  first,  second,  and  third  baking  should  be  carefully  observed 
for  the  purpose  of  getting  an  even  temper  in  the  piece,  and  thereby 
preventing  it  from  crazing  or  cracking  in  cooling. 

The  enamel  being  thoroughly  fused,  the  piece  is  withdrawn  from 
tbe  heated  muffle,  and  passed  into  another,  outside  of  the  furnace. 
This  muffle  should  be  made  quite  hot  before  the  denture  is  placed 
in  it,  in  order  to  prolong  the  cooling  process;  for  if  the  piece  is 
cooled  too  rapidly  it  is  rendered  more  fragile.  It  is  well  to  let  the 
case  remain  in  the  cooling  muffle,  with  the  mouth  of  it  closed,  sev- 
eral hours  before  exposing  it  to  the  air.  By  baking  just  at  night 
the  piece  will  be  in  proper  condition  to  finish  up  the  next  morning. 
Fig.  in  shows  the  case  completed. 

The  finishing  process  consists  simply  in  smoothing  and  polish- 
ing the  plate  and  burnishing  the  rim.  It  is  then  ready  to  be  adjusted 
to  the  mouth.  In  baking,  great  care  is  necessary  to  prevent  the 
piece  from  becoming  gassed.  This  can  be  avoided  by  allowing  the 
gas  to  escape  entirely  from  the  burning  coal  or  coke  in  the  furnace 


CONTINUOUS-GUM        DENTURES.  27 1 

before  the  piece  is  introduced  into  the  muffle.  The  presence  of  gas 
is  indicated  by  the  blue  flame  escaping  from  the  coal.  When  the 
fire  becomes  clear,  it  is  then  safe  to  introduce  the  case  to  be  baked 
(as  before  described)  into  the  muffle.  Pure  anthracite  coal  is  the 
best  for  this  purpose  .when  the  ordinary  furnaces  are  employed,  as 
it  maintains  a  longer  and  stronger  heat  than  coke.  Bituminous 
coal  is  not  good  for  this  kind  of  work  unless  first  converted  into 
coke.  With  the  electric  furnace,  however,  the  danger  or  possibility 
of  gassing  is  entirely  overcome. 

It  often  occurs  that  the  natural  gums  will  change  more  or  less 
after  the  teeth  are  inserted.  In  such  cases  a  new  impression  should 
be  taken  from  the  mouth  and  a  fusible  die  formed.  The  denture  is 
then  placed  upon  the  die,  and  it  will  be  seen  at  once  where  the 
change  has  taken  place ;  then,  with  the  piece  resting  upon  the  die, 
the  artificial  gum  may  be  chipped  off  with  a  small  hammer  and 
chisel.  The  platinum  plate,  being  soft,  can  be  refitted  to  the  die 
very  accurately  with  a  burnisher,  hammer,  and  small  driver  made 
for  the  purpose.  A  new  coat  of  body  is  then  applied  where  the 
plate  has  been  refitted,  and  then  baked,  cooled,  enameled,  and  baked 
again — still  observing  the  same  directions  as  detailed  in  the  manage- 
ment of  new  pieces. 

Repairing. — If  the  tooth  gets  broken  (a  mishap  which  seldom 
occurs  by  use  in  the  mouth)  it  can  be  replaced  with  another  by 
grinding  out  the  remaining  portion  of  the  broken  tooth,  and  the  gum 
covering  the  neck  of  same,  and  then  fitting  a  new  one  in  its  place. 
This  tooth  need  not  be  soldered  to  the  inside  rim;  it  is  sufficient  to 
grind  a  small  notch  or  groove  in  the  enamel  which  covers  the  lingual 
side  of  the  rim  for  the  pin  of  the  tooth  to  fit  into.  The  pin  resting 
in  the  groove  is  covered  with  the  body  at  the  same  time  it  is  applied 
around  the  base  of  the  tooth,  and  when  this  body  is  baked  the  tooth 
will  become  firmly  fastened  in  place  of  the  broken  one.  Any  num- 
ber of  teeth  that  may  be  required  can  be  replaced  in  this  way.  If  it 
is  desired  to  change  the  position  of  one  or  more  teeth,  or  to  make 
'  them  longer,  this  can  also  be  done  as  described  above,  with  the  addi- 
tional precaution,  to  press  softened  wax  upon  the  inside  of  the  teeth 
and  palatal  arch  of  the  denture  before  the  others  are  removed — this 
wax  will  serve  as  a  guide  or  index  as  to  the  relative  change  to  be 
made,  and  also  to  sustain  the  teeth  in  place  while  they  are  being 
fitted  as  desired  to  the  denture.     The  wax  soon  becomes  hard,  and 


-/- 


MECHANICAL    DEXTISTRV. 


is  readily  removed  as  each  successive  tooth  is  ground  and  adjusted 
in  its  proper  place. 

When  the  teeth  are  thus  fitted  with  each  pin  accurately  pressed 
into  the  groove  prepared  for  it,  and  the  wax  being  placed  upon  the 
inside  to  support  the  teeth  in  the  proper  position,  body  is  filled  in 
around  the  base  of  the  new  ones,  which  are  carved,  trimmed,  and 
brushed,  so  as  to  save  the  crowns  of  the  teeth  clean  and  properly 
defined.  The  wax  is  then  carefully  removed  from  the  piece,  and 
more  body  is  filled  in  around  the  teeth  upon  the  inside — filling  up 
the  grooves  over  the  pins,  and  then  carving,  trimming,  etc.,  as  be- 
fore, to  give  it  the  desired  form.  This  done,  if  the  teeth  are  set  a 
little  apart,  and  it  is  desired  to  keep  them  in  that  position,  take  a 
little  piece  of  asbestos  and  gently  press  it  in  between  the  teeth  at 
the  cutting  edges ;  this  will  prevent  them  from  being  drawn  to- 
gether when  the  body  is  being  baked.  The  piece  is  now  ready  for 
the  furnace,  but  it  should  not  be  baked  hard  enough  to  gloss  the 
newly-applied  body ;  it  should  have  more  the  appearance  of  Parian 
marble. 

This  being  done,  it  is  then  withdrawn  from  the  furnace  and  trans- 
ferred to  a  cooling  muffle,  as  before  described.  When  sufficiently 
cool,  the  gum  enamel  is  applied  and  baked  with  a  sharp  heat  until 
it  becomes  smooth  and  glossy.  To  prevent  the  old  gum  from  bleach- 
ing or  becoming  lighter  colored  in  consequence  of  repeated  bakings, 
a  very  thin  coating  of  fresh  gum  enamel  should  be  lightly  brushed 
over  the  entire  enameled  surface  of  the  piece.  The  enamel  thus 
applied  should  be  mixed  with  water,  quite  thin,  so  as  to  flow  evenly 
over  the  surface  when  applied  with  a  camel's-hair  brush.  This 
should  be  done  before  the  last  baking,  that  the  whole  may  be  fused 
at  the  same  time.  Experience  and  judgment  are  essential  requisites 
in  order  to  produce  good  practical  results.  For  example,  if  the 
carving  of  the  body  is  not  properly  clone,  the  form  and  shading  of 
the  gum  and  roof  will  not  appear  natural  when  the  work  is  finished ; 
if  the  gum  enamel  is  put  on  too  thick,  it  will  produce  a  dark  red 
color;  if  not  thick  enough,  it  will  be  too  light;  if  fused  too  hard,  it 
will  be  liable  to  craze  or  crack;  if  not  hard  enough,  it  will  be  rough 
or  granular;  if  the  piece  becomes  gassed  in  baking,  it  will  be  porous 
and  of  a  bluish  color. 

Dr.  Haskell's  Methods. — "  It  should  be  borne  in  mind,"  says 
Dr.    Haskell,    "  that    the    strength    of    this    work    depends    mainly 


CONTINUOUS-GUM        DENTURES.  273 

upon  the  metal,  and  not  upon  the  porcelain,  though  the  latter  adds 
to  its  strength.  While  platinum  is  a  very  soft  metal,  yet,  by  means 
of  various  devices,  the  plate,  with  the  teeth  properly  soldered  on, 
and  ready  for  the  porcelain,  can  be  made  very  stiff  and  strong,  there- 
fore everything  that  can  be  done  to  secure  a  strong  foundation  should 
be  carefully  observed. 

"  The  plate  should  be  of  the  best  French  material  (not  melted 
scraps  and  old  plates),  29  to  30  gage  for  the  upper,  and  26  to  28  for 
the  lower,  and  should  be  swaged  on  Babbitt  metal  dies.  The  plate 
is  then  tried  in  the  mouth,  and  if  the  fit  is  found  to  be  correct, 
arrange  the  articulating  wax,  secure  the  '  bite,'  and  make  the  articu- 
lating model. 

"  The  back  of  the  plate  should  be  doubled,  for  the  following  rea- 
sons :  It  imparts  increased  strength ;  leaves  some  margin  for  change, 
in  case  of  necessity,  after  the  work  is  in  the  mouth;  protects  the 
edge  of  the  porcelain,  and  admits  of  a  neater  finish.  This  '  doubler ' 
should  be  about  -^  of  an  inch  wide,  with  the  edge  turned  up  slightly 
to  receive  the  porcelain.  Around  the  outer  edge,  solder  a  flattened 
wire,  Jg  of  an  inch  wide,  or  less,  and  22  gage,  bringing  the  ends  to 
meet  the  turned  edge  of  the  doubler.  This  strengthens  the  plate, 
and  affords  a  good  round  finish  to  the  edge,  as  well  as  protection  to 
the  porcelain.  This  is  easily  put  on  after  a  little  practice,  and  is  far 
preferable  to  turning  the  edge  of  the  plate  with  pliers,  or  otherwise. 
Pure  gold  should  always  be  used  for  soldering,  and  with  just  enough 
borax  (using  very  little)  to  give  direction  to  the  flow  of  solder. 

"  Then  comes  the  arrangement  of  the  teeth,  and  this  should  al- 
ways be  done  in  the  mouth,  the  articulating  model  being  only  a  pre- 
liminary guide ;  for  by  the  mouth  alone  can  one  determine  the  correct 
expression  and  arrangement  desired;  and  it  is  just  here  that  three- 
fourths  or  more  of  the  artificial  dentures  fail  in  an  utter  lack  of 
artistic  skill.  In  this  work  there  is  ample  opportunity  for  the  dis- 
play of  taste  and  skill,  so  that  perfection  itself  is  attained  at  the 
hands  of  the  true  artist. 

"  The  investing  process  comes  next.  First,  a  coat  of  shellac  over 
the  teeth  to  prevent  etching  (although,  if  this  occurs,  it  is  not  a 
matter  of  much  account,  as  the  baking  remedies  it).  Then  a  thin 
coat  of  clear  plaster;  next  plaster  and  asbestos,  one  part  of  the  lat- 
ter to  two  of  the  former.  Let  the  portion  under  the  plate  extend 
18 


2/4  MECHANICAL  DENTISTRY. 

at  least  one  inch  back  of  the  latter,  as  this  bottom  portion  is  to  be 
retained  on  which  to  bake  the  case;  invest  the  whole  ^  of  an  inch 
thick.  Warm  the  case  until  the  plate  is  sufficiently  heated  to  remove 
the  wax  easily;  dash  boiling  water  over  it  (this  is  the  best  method 
to  remove  wax  adhering  to  teeth  and  plate  in  all  kinds  of  work). 
The  backings  should  be  continuous  and  be  lapped  on  to  the  plate, 
for  in  this  is  the  mainstay  of  the  work  for  strength.  Cut  patterns 
in  tin  or  lead,  three  pieces,  one  for  the  six  front  teeth,  and  one  for 
each  side,  lapping  over  the  cuspid  teeth ;  the  foot-piece  should  lap 
on  to  the  plate  about  -^  of  an  inch.  No  borax  is  needed.  The  gold 
should  be  melted  and  rolled  into  a  ribbon  as  thin  as  possible,  and 
cut  in  small  pieces  and  laid  under  the  lap,  or  foot-piece,  and  a  piece 
under  each  pin.  The  backings  can  be  fitted  more  easily  by  splitting 
the  foot-piece.  The  most  convenient  method  of  soldering  is  in  the 
furnace,  being  careful  not  to  let  it  remain  too  long,  so  as  to  fuse 
the  enamel  on  the  teeth.  If  a  pin  should  fail  to  solder,  it  is  imma- 
terial, as  the  '  body  '  will  hold  it. 

"  After  cooling,  remove  the  plaster  and  save  the  base.  Place  the 
plate  on  the  articulating  model,  and  if  it  is  sprung,  press  it  into  place, 
which  is  very  readily  done. 

"  Apply  the  '  body  '  mixed  with  water,  quite  thin,  by  means  of  an 
oval-pointed  knife,  occasionally  jarring  with  handle  of  spatula,  and 
as  the  moisture  comes  to  the  surface,  absorb  with  a  cloth ;  after  it  is 
well  filled  into  all  interstices,  apply  it  thicker,  jarring,  absorbing,  and 
packing  hard,  until  enough  is  on  the  outside  to  produce  the  proper 
shape  and  contour  of  the  lips.  Then  apply,  with  the  curved  point 
of  the  knife,  the  body  to  the  lingual  side  of  the  plate,  same  as  on 
the  outside,  but  only  a  thin  coat  on  the  plate.  Trim  around  the  necks 
of  the  teeth,  remove  all  particles  from  between  with  a  quill  tooth- 
pick, and  brush  all  particles  off  the  surface  of  the  teeth  and  exposed 
portions  of  plate,  and  the  case  is  ready  for  baking. 

"  The  furnace  shown  in  Fig.  26  is  preferable ;  and  in  setting  the 
'  muffle,'  see  that  the  vent  hole  in  the  top  is  clear;  this  is  for  escape 
of  gas  that  may  be  in  the  muffle  and  would  injure  the  work.  Fasten 
the  front  end  with  fire-clay,  but  leave  the  back  end  free.  Set  the 
case  10  or  12  inches  from  the  opening,  move  forward,  every  few 
minutes,  a  couple  of  inches,  until  it  is  in  the  muffle;  place  it  within 
two  inches  of  the  back,  and  close  the  door.     If  the  heat  is  right, 


"  CONTINUOUS-GUM  "    DENTURES.  275 

five  or  ten  minutes  will  suffice ;  still,  it  must  be  looked  at  so  as  not 
to  get  too  much  heat.  This  first  bake  should  be  only  a  glaze.  Re- 
move to  a  muffle  on  the  hearth  and  close  up  tight.  When  cool,  place 
on  the  model,  and,  if  sprung,  press  it  into  place.  Next  fill  up  all 
the  cracks  with  very  thin  body,  jarring  with  handle  of  the  spatula 
often,  so  that  the  material  will  fill  up  thoroughly ;  then  spread  on 
thicker  until  the  proper  shape  and  fullness  are  secured,  trimming 
around  the  teeth,  and  doing  as  previously  described,  and  bake  as 
before.  After  cooling,  the  enamel  is  to  be  put  on  the  same  as  the 
body,  applying  only  a  thin  and  uniform  coat.  The  rugae  can  be 
produced  in  the  body  or  in  the  gum.  The  enamel  should  have  a 
thoroughly  glossy  appearance  when  ready  to  be  removed  from  the 
furnace. .  Heated  cooling  muffles  are  unnecessary,  as  the  case  itself 
will  heat  the  muffle  all  that  is  necessary. 

"  Lower  sets  are  better  without  a  binding,  as  it  is  sometimes 
necessary  to  file  or  grind  away  the  edge. 

"  The  case  is  finished  by  filing  and  polishing  the  exposed  metal 
surface,  not  doing  anything  to  the  upper  surface. 

"  A  '  defined '  air-chamber  is  rarely  necessary ;  a  Cleveland  cham- 
ber never.  Raise  the  plate  over  the  hard  palate  with  a  thin  film  of 
wax  on  the  plaster  cast,  chamfering  off  the  edges  completely ;  scrape 
the  plaster  model  across  the  back,  except  right  in  the  center,  accord- 
ing to  the  softness  of  the  palate. 

"  This  work  is  not  advisable  for  partial  sets,  except  in  some  par- 
tial lower  cases  where  there  are  no  detached  teeth.  In  these  cases 
the  plate  should  be  at  least  two  thicknesses  across  the  back  of  the 
front  teeth,  and  resting  well  up  on  the  necks  of  the  same. 

"  Repairing. — Very  few  seem  to  know  how  to  prepare  a  case  for 
repairing.  Invest  it  in  plaster  and  asbestos  at  least  ]/2  of  an  inch 
deep ;  place  in  the  muffle  before  lighting  the  fire,  and  allow  it  to 
remain  with  the  door  open,  as  the  fire  comes  up,  until  it  is  red  hot; 
then  remove,  cool,  and  thoroughly  clean  off  the  plaster,  preserving 
the  base,  and  it  can  be  run  into  the  furnace  with  as  little  danger  of 
cracking  as  if  it  had  never  been  worn. 

"  Grind  out  the  remains  of  the  teeth  below  the  margins  of  the 
gum ;  select  a  rubber  tooth,  as  it  is  easier  to  get  and  just  as  good 
as  one  made  for  this  work,  filing  off  the'pins;  hold  with  wax  until 
a  little  plaster  and  asbestos  can  be  placed  over  it  and  the  adjoining 


2^6  MECHANICAL    DENTISTRY. 

teeth;  thoroughly  remove  the  wax  and  put  on  repairing  body,  and 
bake;  cool,  put  on  the  gum,  having  previously  ground  off  a  portion 
of  the  old  gum  if  it  is  a  very  old  case,  and  put  on  just  a  little  new, 
and  bake  as  at  first. 

"  If  blisters  occur,  grind  into  them  and  fill  with  body  and  gum, 
three  to  one,  press  hard,  and  enamel." 

Dr.  Ambler  Tees'  Methods  and  Formulas. — The  late  Dr.  Tees 
described  his  work  as  follows :  "  Continuous-gum  work  is  mounted 
upon  a  swaged  plate  of  pure  platina,  about  No.  29,  American  gage. 
The  lowest  plate,  to  insure  strength,  is  made  of  two  pieces  soldered 
together,  one  being  large  enough  to  allow  for  a  rim.  In  a  partial 
lower  set,  an  additional  piece  of  iridionized  platina  is  soldered  to  the 
part  covering  the  lingual  gums  of  the  remaining  natural  teeth.  Plain 
teeth,  with  single  long  pins,  made  for  the  purpose  by  tooth  manu- 
facturers, are  soldered  to  the  plate  with  pure  gold  (24  k.),  which 
alone  is  used  as  a  solder  in  this  work,  since  the  copper  and  silver  con- 
tained in  alloyed  gold  will  discolor  the  gum  enamel.  The  silicious 
materials  called  body  and  gum  enamel  are  then  applied  around  the 
necks  of  the  teeth,  and  upon  the  lingual  portion  of  the  plate,  by 
means  of  small  spatulas,  and  carved  to  imitate  the  contour  of  the 
gum. 

'  The  investment  used  for  retaining  the  teeth  in  position  while 
being  soldered  is  composed  of  two  parts  of  plaster  and  one  of  asbes- 
tos ;  before  applying  this,  the  teeth  should  be  coated  with  a  thick 
varnish  of  shellac  and  alcohol,  to  prevent  the  teeth  being  etched  in 
soldering.  The  backing  is  fitted  most  conveniently  by  making  it  of 
three  pieces ;  the  pins  are  bent  down  over  it,  and  soldered  with  pure 
gold.  After  soldering,  the  investment  is  removed,  and  the  teeth  and 
the  plate  brushed  with  soap-suds  and  powdered  pumice-stone  and 
washed  off  with  clean  water.  The  first  coat  of  body  is  then  applied, 
moistened  with  clean  water  to  the  consistency  of  soft  putty,  as  a 
foundation,  no  effort  being  made  to  imitate  the  contour  of  the  gums ; 
separations,  however,  are  made  between  the  teeth,  so  that  the  body 
may  fuse  around  each  tooth  separately,  and  prevent  it  being  drawn 
from  position  by  the  shrinkage  of  the  body.  It  is  then  fused  in  the 
muffle,  and  placed  in  a  cool  muffle  for  thirty  minutes.  After  adjust- 
ing it  upon  the  articulator,  it  is  ready  for  the  second  coat  of  body. 
In  applying  this,  an  artistic  effort  is  made  to  imitate  the  contour  of 
the  gums ;  and  by  making  elevations  and  depressions  in  appropriate 


CONTINUOUS-GUM  "   DENTURES.  277 

position,  the  lights  and  shades  of  the  natural  gums  may  be  simu- 
lated, especial  attention  being  paid  to  the  rugae.  This  coat  is  vitri- 
fied and  not  fused.  After  it  is  cool  and  again  adjusted  upon  the 
articulator,  the  gum  enamel  is  applied,  the  spatulas  being  used  for 
the  purpose.  It  is  moistened  with  clean  water,  a  little  thinner  than 
the  body,  and  laid  on  a  little  at  a  time,  about  the  thickness  of  26 
plate.  This  is  fused  and  allowed  to  remain  in  the  cool  muffle  for 
an  hour  and  a  half.  The  platina  is  then  rubbed  with  pumice-stone, 
an  orange-wood  stick  being  used,  and  the  rim  filed,  stoned,  and  bur- 
nished, when  the  set  will  be  ready  for  the  mouth. 

"  When  a  set  is  to  be  repaired,  the  mucus  should  be  burnt  off 
before  any  fresh  body  is  applied.  To  accomplish  this,  it  should  be 
invested  in  plaster  and  asbestos,  and  heated  to  redness  over  a  gas 
or  coal-oil  stove,  or  upon  the  coals  in  a  range.  The  investment 
should  then  be  removed,  the  set  washed  with  soap-suds  and  pumice- 
stone,  and  again  heated  to  redness  upon  a  slide  in  the  muffle.  The 
new  tooth,  after  being  carefully  ground  against  the  gum,  is  held  in 
position  by  plaster  and  asbestos  on  the  palatine  surface,  a  very  small 
quantity  being  sufficient ;  after  it  has  set,  gum  enamel  is  worked  into 
the  joint  at  the  neck  and  fused  in  the  muffle.  The  body  and  gum 
enamel  are  then  applied  to  the  palatine  surface,  after  the  pin  is  sol- 
dered to  the  old  backing,  and  then  fused.  This  plan  obviates  the 
old  method  of  investing  the  whole  set  in  plaster  and  asbestos." 

Body  and  gum  enamel  for  continuous-gum  work  was  manufac- 
tured by  the  late  Dr.  Tees,  according  to  the  following  formulas  and 
methods  of  compounding : 

He  furnished  three  shades  of  gum  enamel — pale,  medium,  and 
dark.     The  body  as  made  by  him  is  composed  of : 

Feldspar,    2  ozs. 

Dental  glass,    8  dwts. 

Kaolin,     3   dwts. 

The  materials  are  ground  together  in  a  moistened  state,  in  a 
wedgewood  mortar,  for  about  an  hour ;  then  dried ;  again  ground 
for  ten  minutes,  and  fused  in  a  crucible  in  a  coke  fire,  or  upon  a 
slide  in  the  muffle.  After  being  pulverized,  two  grains  of  titanium 
to  each  ounce  are  added  and  thoroughlv  mixed. 


2j8  MECHANICAL   DENTISTRY. 

The  gum  enamel  is  composed  of : 

Feldspar, 2  ozs. 

Dental  glass 10  dwts. 

Gum   frit,    Vi   dwt. 

These  materials  are  ground  together  in  a  moistened  state,  for 
about  an  hour,  in  a  wedgewood  mortar;  then  dried,  ground  again 
for  ten  minutes,  and  fused — upon  a  slide  rubbed  with  fine,  dry  silex 
— in  the  muffle  of  the  furnace ;  again  pulverized,  and  sufficient  addi- 
tional gum  frit  mixed  in  with  a  spatula  to  give  the  desired  shade. 

The  materials  fuse  readily  and  will  not  check  in  cooling. 

Application  of  Continuous  Gum  to  Partial  Sets. — The  follow- 
ing method  of  constructing  partial  sets  of  artificial  teeth  with  con- 
tinuous gum  is  taken  from  a  practical  paper  on  this  process  by  Dr. 
W.  B.  Roberts: 

"  Partial  cases  may  be  made  of  continuous  gum ;  but  the  work 
is  so  various  in  its  nature  that  the  dentist  must  necessarily  depend 
much  upon  his  own  judgment.  Difficult  cases  will  constantly  pre- 
sent themselves  that  will  require  the  exercise  of  much  study  and 
ingenuity,  in  which  the  general  instruction  that  can  be  given  in  words 
may  be  of  but  little  service.  The  first  attempt  of  this  kind  in  my 
own  experience  was  in  replacing  two  central  incisors.  Taking  two 
continuous-gum  teeth,  I  placed  upon  them  a  platinum  lining,  slitting 
this  down  along  the  edge  of  one  tooth  nearly  through  the  piece  and 
up  the  edge  of  the  other  tooth  by  a  parallel  cut,  leaving  the  two 
parts  joined  together  by  a  narrow  slip.  This  allowed  sufficient  mo- 
tion between  the  teeth,  so  that  they  could  be  adjusted  as  desired.  I 
then  placed  a  small  piece  of  tissue-paper  on  the  plaster  model,  cover- 
ing the  spot  to  be  occupied  by  the  teeth  and  gum,  to  prevent  the 
adhesion  of  the  body  to  the  plaster,  and  holding  the  two  incisors  in 
their  places,  worked  the  body  into  all  the  depressions  of  the  gum 
and  around  the  roots  of  the  teeth.  It  was  then  all  removed  from 
the  model,  and  placed  in  a  paste  of  pulverized  silex,  or  plaster  and 
asbestos,  upon  a  slide,  and  baked  as  described  for  full  sets.  The 
little  slip  of  platinum  kept  the  two  teeth  in  place.  The  work  shrunk 
somewhal  ;  but  this  was  remedied  by  again  placing  the  piece  upon 
the  model  with  the  intervention  of  tissue-paper  covered  with  a  thin 
coating  of  body.  Into  this  I  pressed  the  piece  till  it  occupied  its 
true  place,  and  then  filled  in  again  with  more  body  all  the  crevices 
an  mud  the  roots  of  the  teeth,  and  rebaked. 


"  CONTINUOUS-GUM  "    DENTURES.  279 

"After  enameling,  if  the  work  has  been  carefully  and  skilfully 
done  upon  this  plan,  it  will  be  as  fine  a  piece  in  appearance  and  fit 
as  can  be  made.  It  may  then  be  soldered  to  a  gold  plate,  and  the 
little  strip  of  platinum  between  the  teeth  be  cut  out.  With  the 
body  and  gum  formerly  in  use  many  difficulties  were  encountered 
from  discoloration  of  the  gum,  or  from  other  injuries  incurred  in 
soldering.  But  with  Roberts'  material  these  are  easily  avoided,  and 
the  piece  can  be  treated  the  same  as  block  or  single  gum  teeth.  In 
partial  sets  on  entire  plates  of  platinum  trouble  has  sometimes  been 
experienced  by  the  enamel  giving  way  upon  the  small  narrow  points 
that  connect  the  teeth  with  the  plate  by  the  shock  occasioned  in  bit- 
ing, consequently  I  have  left  these  points  uncovered,  and  used  two 
or  three  thicknesses  of  platinum  to  give  greater  strength.  But 
where  this  is  likely  to  occur,  gold  plates  would  be  preferable,  if 
nicely  adapted  with  single  gum  teeth,  or  blocks  of  continuous  gum, 
as  the  case  might  require.  I  have  also  applied  continuous  gum  in 
cases  where  the  natural  teeth,  from  one  to  five  in  number,  were 
left  in  the  mouth,  by  making  the  plates  as  in  full  sets,  cutting  out 
around  the  natural  ones,  and  raising  a  small  bead,  or  placing  a  light 
wire  around,  about  }i  of  an  inch  or  more  from  the  teeth,  against 
which  the  gum  or  body  is  to  be  finished.  The  points  around  the 
teeth  are  to  be  left  free,  in  order  to  be  burnished  down  in  cases  of 
imperfections  caused  by  the  difficulty  of  obtaining  exact  impressions 
in  these  places.  In  such  cases  I  sometimes  form  a  strong  standard 
of  several  thicknesses  of  platinum  fitting  closely  against  one  or  more 
natural  teeth,  leaving  a  loophole  through  which  to  run  a  gold  clasp 
for  afterward  securing  the  artificial  set. 

"  I  have  also  secured  the  gold  to  the  standard  by  rivets  of  plati- 
num, and  sometimes  by  two  or  three  gold  screws,  not  providing,  in 
these  cases,  the  loophole.  These  methods  are  to  be  preferred  to 
using  solder  for  fastening ;  for,  in  case  of  repair,  the  clasps  are  easily 
removed  without  leaving  any  foreign  substance;  but  in  case  of 
soldering,  however  carefully  they  may  be  removed,  there  will  remain 
some  alloy,  which  in  the  baking  heat  to  which  the  piece  is  to  be 
exposed  will  be  incorporated  with  the  platinum.  Even  so  small  an 
amount  of  silver  as  may  be  in  gold  coin  used  for  solder  will  com- 
municate a  yellowish  tinge  to  the  gum,  spoiling  the  whole  work. 
Many  operators  in  their  early  practice  experienced  this  result,  and 
learned  that  no  alloys,  especially  of  silver  or  copper,  can  be  admis- 


280  MECHANICAL  DENTISTRY. 

sible  for  soldering  this  work.  I  have  tried  platinum  clasps  without 
success,  as  no  elasticity  could  be  obtained,  and  therefore  would  not 
hold  upon  the  teeth.  Another  source  of  mischief  may  properly  be 
noticed  in  this  place.  In  baking,  especially  with  a  new  furnace,  or 
with  muffles  lately  renewed,  either  at  the  first  or  second  heat,  or  it 
may  be  enameling,  the  piece  is  sometimes  changed  in  its  texture  and 
color,  as  is  supposed,  by  the  gases  present,  and  the  phenomenon  is 
called  gassing  the  piece.  The  body  becomes  porous  and  of  a  bluish 
color.  When  this  occurs  there  is  no  remedy  but  to  place  it  on  the 
metallic  die,  remove  the  whole  of  the  injured  part,  and  replace  it 
with  a  new  coating  of  body  and  gum.  The  teeth  are  seldom,  if  ever, 
thus  affected.  As  a  precaution,  the  muffles  should  be  well  ventilated 
with  holes  for  the  passage  of  the  heated  air  and  gases." 


CHAPTER  XXIII. 
RUBBER  OR  VULCANITE  BASE. 

While  there  are  undoubtedly  many  important  uses  to  which  vul- 
canized india-rubber  may  be  applied  in  the  practical  departments 
of  dentistry,  and  for  which  it  would  be  difficult  to  find  an  adequate 
substitute,  yet  there  are  accumulating  evidences  leading-  to  the  con- 
clusion that  its  abandonment,  as  a  base  for  artificial  dentures,  by 
intelligent  and  conscientious  practitioners,  except  in  rare  cases,  or 
where,  for  pecuniary  reasons,  a  more  expensive  base  is  not  admissible, 
is  an  event  of  the  not  distant  future. 

This  anticipated  result,  in  respect  of  a  material  which  has  been 
almost  universally  employed  as  a  base  for  the  past  twenty  years,  is 
assured  by  the  confirmed  and  steadily  increasing  distrust  of  its  suit- 
ableness for  the  purpose  indicated,  and  the  growing  tendency  in  the 
profession  to  return  to  higher  and  less  objectionable  forms  of  sub- 
stitution in  respect  to  material  and  construction. 

While  the  statements  made  in  former  editions  of  this  work  in 
regard  to  rubber  as  a  base  reflected,  as  the  author  believed,  the  esti- 
mate of  its  fitness  by  the  profession  generally,  what  is  now  written, 
the  editor  believes,  embodies  the  present  judgment  of  the  mass  of 
enlightened  practitioners  in  reference  to  its  unsuitableness  as  a  base 
for  artificial  dentures. 

General  Properties  of  India-rubber. —  Caoutchouc,  gum-elastic, 
or  india-rubber  exists  as  a  milky  juice  in  several  plants,  but  is  ex- 
tracted chiefly  from  the  Siphonia  cahuca,  which  grows  in  South 
America  and  Java.  It  is  discharged  through  the  numerous  inci- 
sions made  in  the  tree  through  the  bark,  and  is  spread  upon  clay 
molds,  and  dried  in  the  sun,  or  with  the  smoke  of  a  fire,  which  black- 
ens it.  The  juice  when  first  obtained  is  of  a  pale  yellow  color,  of 
about  the  consistency  of  cream,  and  has  a  specific  gravity  of  about 
1.012.  In  the  process  of  drying  55  per  cent,  is  lost,  the  residuary 
45  being  elastic  gum.  It  immediately  coagulates,  by  reason  of  its 
albumin,  on  application  of  heat,  the  elastic  gum  rising  to  the  sur- 

281 


282  MECHANICAL    DENTISTRY. 

face.  The  specific  gravity  of  the  juice  is  diminished  by  inspissa- 
tion,  becoming  0.925  when  hard,  and  cannot  be  permanently  in- 
creased by  any  degree  of  pressure.  When  once  stiffened  by  cold 
or  continued  quiescences  it  cannot  be  restored  to  its  original  condi- 
tion of  juiciness. 

The  inspissated  juice,  or  crude  rubber  of  commerce,  is  altogether 
insoluble  in  water  or  alcohol,  but  is  readily  soluble  in  ether  deprived 
of  its  alcohol  by  washing,  affording  a  colorless  solution.  On  evap- 
oration of  the  ether,  the  gum  resumes  its  original  condition.  It 
swells  to  thirty  times  its  bulk  when  treated  with  hot  naphtha,  and  if 
triturated  in  this  condition  in  a  mortar,  and  pressed  through  a  sieve, 
furnishes  a  homogeneous  varnish  employed  in  the  preparation  of  a 
waterproof  cloth. 

Caoutchouc  is  soluble  in  the  fixed  oils,  but  is  not  readily  decom- 
posed by  cold  sulphuric  acid  or  diluted  nitric  acid,  and  is  unaffected 
by  either  muriatic  acid  gas,  sulphurous  acid  gas,  fluosilicic  acid,  am- 
monia, or  chlorin,  nor  is  it  dissolved  by  the  strongest  caustic  potash 
lye.  even  at  a  boiling  heat,  and  is  therefore  highly  esteemed  as  an 
appliance  of  the  chemical  laboratory.  According  to  the  experiments 
of  Ure,  Faraday,  and  others,  caoutchouc  contains  no  oxygen,  as  al- 
most all  other  solid  vegetable  products  do,  but  is  a  mere  compound 
of  carbon  and  hydrogen,  in  the  proportion  of  three  atoms  of  the  for- 
mer to  two  of  the  latter.  From  this  property  of  resisting  the  corro- 
sive action  of  acid  vapors,  and  its  tenacity  of  adhesion  to  glass, 
caoutchouc,  when  melted,  forms  a  very  excellent  lute  for  chemical 
apparatus. 

Such  are  some  of  the  properties  of  this  remarkable  product,  the 
uses  of  which  have  been  almost  immeasurably  extended  since  the 
first  successful  efforts  to  produce  artificial  induration  by  Charles 
Goodyear  in  1844. 

Compounding  Rubber  for  Dental  Purposes. — India-rubber  is 
prepared  for  vulcanizing  by  incorporating  with  it,  in  varying  pro- 
portions, either  sulphur  alone  or  some  of  its  compounds,  sulphur 
being  an  essential  component  of  all  vulcanizable  gum  compounds. 
For  dental  purposes,  the  coloring  is  effected  in  most  preparations  by 
the  introduction  of  vermilion  (sulphuret  of  mercury).  These  sub- 
stances, properly  combined,  are  subjected  to  artificial  heat  for  a 
specified  time,  producing  a  hard,  horn-like  substance,  possessing 
the   qualities   of   lightness,   strength,    durability,    imperviousness   to 


RUBBER  OR  VULCANITE  BASE.  283 

fluids,  insolubility  in  the  oral  secretions,  unchangeableness  on  ex- 
posure to  ordinary  temperatures,  etc. 

Method  of  Constructing  an  Entire  Denture  in  a  Base  of  Rub- 
ber.— As  the  manipulations  concerned  in  the  construction  of  a 
full  upper  set  differ  in  no  essential  respect  from  those  required  in 
the  formation  of  a  denture  for  the  inferior  arch,  except  as  the  two 
differ  in  conformation,  requiring  corresponding  modifications  of 
practice  which  will  readily  suggest  themselves,  it  will  be  sufficient 
to  describe  the  method  of  constructing  an  entire  denture  for  the 
upper  jaw. 

An  impression  of  the  mouth  is  first  secured  in  the  usual  manner, 
and,  as  has  been  stated,  plaster-of-Paris  is  preferable  to  any  other 
material  for  the  purpose.  As  rubber,  when  rendered  plastic  by  heat 
and  subjected  to  pressure,  receives  a  distinct  and  perfect  impress  of 
the  face  of  the  model,  it  is  important  that  the  latter  should  be  as 
smooth  upon  its  surface,  and  as  free  from  faultiness  of  form  or 
surface  blemish,  as  possible.  From  the  impression  a  plaster  model 
is  obtained,  and  if  an  air-chamber  is  required,  it  may  be  secured 
either  by  cutting  out  from  the  impression  before  filling  in  with 
plaster,  for  the  model,  or  it  may  be  raised  upon  the  model  after 
the  latter  has  been  separated  from  the  impression.  For  the  latter 
purpose  lead  is  often  used,  but  sheet-tin,  cut  to  the  required  form, 
is  preferable,  as  the  former  leaves  a  tenacious  coating  of  oxid  adher- 
ing to  the  plate. 

A  temporary  or  model  base-plate  is  next  conformed  as  accurately 
as  possible  to  the  face  of  the  model,  and  for  this  purpose  the  pre- 
pared gutta-percha,  paraffin,  and  wax,  or  modeling  compound 
worked  into  thin  sheets  may  be  used,  or  a  die  may  be  secured  and 
a  trial  plate  struck  up  from  block  tin.  Though  the  latter  requires 
more  labor,  it  gives  more  satisfactory  and  accurate  results.  The 
former  may  be  softened  either  by  subjecting  them  to  a  dry  heat 
until  sufficiently  plastic,  or  by  immersing  in  hot  water.  The  face 
of  the  model  being  previously  well  saturated  with  cold  water  to 
prevent  the  wax  or  gutta-percha  from  adhering,  the  latter  is 
pressed  or  .molded  accurately  to  the  model  with  the  fingers  moist- 
ened with  cold  water,  heating  such  portions  from  time  to  time  as 
'do  not  readily  yield  to  pressure  until  an  accurate  adaptation  of  all 
•portions  of  the  plate  is  secured ;  then  trim  to  the  required  dimen- 
sions. 


284  MECHANICAL  DENTISTRY. 

Having  fitted  the  temporary  plate  to  the  model,  it  is  placed  in 
the  mouth  with  a  wax  guide  or  rim  attached,  when  the  latter  is 
trimmed  to  the  required  width,  fullness,  and  contour,  and  the 
"  bite  "  of  the  under  teeth  secured ;  it  is  then  removed  and  placed 
in  its  proper  position  on  the  model,  which  is  placed  in  an  articu- 
lator, with  the  antagonizing  model,  the  latter  being  obtained  in  the 
manner  described  in  connection  with  the  metallic  plate-base  (page 
242).  The  mode  of  procedure  in  cases  of  entire  dentures  for  the 
upper  and  lower  jaws  differs  in  no  respect  from  that  practised  when 
gold  or  other  metallic  plate  is  used  as  a  base. 

Arranging  the  Teeth. — Having  secured  an  antagonizing  model, 
the  teeth  are  selected  and  arranged  upon  the  temporary  plate  in  the 
usual  manner.  The  porcelain  teeth  used  in  this  process  are  more 
commonly  in  the  form  of  blocks  or  sections.     Figs.   112  and   113 

Fig.   112. 


exhibit  the  marked  peculiarities,  and  the  proper  arrangement  of  an 
artistically  designed  set  of  gum  or  block  teeth.  The  increased 
strength  of  attachment  formed  by  the  greater  number  of  pins  also 
renders  them  more  permanent  and  enduring  than  single  gum  teeth. 
Teeth  made  expressly  for  rubber  base  were  originally  manufactured 
with  plain  platina  pins,  longer  and  heavier  than  those  used  in  con- 
nection with  metallic  plates.  These,  when  used,  were  curved  and 
pressed  together,  forming  loops  or  hooks  to  prevent  them  with- 
drawing from  the  rubber.  Subsequently,  however,  the  detachment 
of  the  teeth  was  more  securely  and  certainly  provided  against  by 
the  substitution  of  headed  pins,  which  rendered  their  withdrawal 
from  the  rubber  impossible.  For  this  valuable  improvement  the 
profession  is  indebted  to  the  late  Dr.  S.  S.  White,  whose  genius, 
enterprise,  and  intelligence  were  so  long  and  unceasingly  tributary 
to  the  needs  of  the  dental  practitioner. 


RUBBER  OR  VULCANITE  BASE. 
Fig.   113. 


^°: 


Fig.   114. 


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f 


^iittiiUMi^iiiiiiiliiiiiUJ^ 


ri  r\ 


J   L_  i   \<.J   V      1 


W\m 


^\r\t 


m\M 


^  !  ^ 


286  MECHANICAL   DENTISTRY. 

The  latest  design  in  the  construction  of  porcelain  teeth  is  shown 
in  Fig.  114.  The  base  of  the  tooth  is  countersunk,  with  headed  pins 
inclosed  within  the  cavity.  It  is  claimed  that  their  close  conformity 
in  contour  to  the  natural  organs  makes  them  much  more  acceptable 
to  the  tongue  than  teeth  backed  in  the  ordinary  manner,  renders 
articulation  easier  and  more  distinct,  and  prevents  disclosure  of 
artificiality  when  the  mouth  is  opened.  In  addition  to  these  advan- 
tages, they  allow  greater  facility  of  adaptation  to  the  maxillary 
ridge.  They  are  particularly  adapted  to  rubber  base  with  cellu- 
loid facing,  or  to  celluloid  base  alone.  Other  forms  of  plain  teeth 
are  placed  upon  the  market,  and  when  they  can  be  employed  more 
artistic  results  may  be  secured  than  is  possible  with  the  gum 
teeth. 

Grinding  and  Jointing  the  Teeth. — In  arranging  the  teeth,  por- 
tions of  the  wax  rim  are  cut  away  to  form  a  bed  for  each  tooth 
or  block,  as  the  case  may  be,  grinding  from  the  base  of  the  latter 
and  from  their  proximate  edges  until  the  proper  position  is  assigned 
to  the  teeth,  and  the  required  antagonism  is  secured.  When  gum 
teeth  are  used;  whether  single  or  in  the  form  of  blocks,  they  should 
be  united  to  each  other  laterally  with  the  greatest  possible  accuracy, 
to  prevent,  as  far  as  practicable,  the  intrusion  of  the  gum  material 
between  them.  To  further  provide  against  this,  various  expedients 
have  been  resorted  to  with  the  view  of  cementing  or  packing  the 
joints  in  order  to  render  them  impervious  to  the  rubber.  The  sub- 
stances usually  recommended  for  this  purpose  are  plaster  or  finely- 
pulverized  silex  or  feldspar  moistened  with  dilute  liquid  silex,  os- 
artificial,  soluble  glass,  gold,  or  tin-foil,  or  fusible  metal  packed  into 
the  joints,  etc.  Of  the  more  destructible  substances  mentioned,  Pro- 
fessor Wildman  very  justly  observes :  "  All  of  these,  in  course  of 
time,  will  yield  to  the  action  of  the  fluids  of  the  mouth ;  and  then 
the  ill-fitted  joints  will  be  receptacles  for  soft  particles  of  food, 
which  will  be  more  objectionable  than  having  them  filled  with  good, 
solid  rubber.  The  best  filling  is  an  accurately  fitted  joint;  when  so 
made,  if  the  enveloping  plaster  is  of  good  quality  and  properly 
mixed,  and  no  undue  force  is  used  in  bringing  the  section  of  the 
fla-1:  together,  there  is  little  danger  of  the  rubber  insinuating  itself 
into  the  joints."  As  properly  remarked,  there  is  no  expedient  which 
will  so  certainly  and  effectually  exclude  the  rubber  as  close-fitting 
joints,  and  if  the  precaution  is  taken  to  secure  an  accurate  and  uni- 


RUBBER  OR  VULCANITE  BASE. 


287 


form  coaptation  of  the  ground  surfaces 
where  they  unite  in  front,  and  the  "  en- 
veloping plaster  is  of  good  quality  and 
properly  mixed,  and  no  undue  force  is 
used  in  bringing  the  sections  of  the  flask 
together,"  there  will,  at  most,  be  but  a 
very  thin  film  of  rubber,  nearly  imper- 
ceptible in  the  finished  work,  and  wholly 
so  in  the  mouth.  To  better  effect  the 
object  stated,  the  writer  has  been  accus- 
tomed, when  uniting  porcelain  blocks, 
to  use  a  small  magnifying  glass,  which 
reveals  inaccuracies  of  coaptation  not 
apparent  to  the  naked  eye. 

The  teeth  having  thus  been  properly 
united  and  arranged,  the  wax  rim 
supporting  them  on  the  lingual  side 
should  be  cut  away  and  carved  with 
heated  instruments,  especially  designed 
for  that  purpose,  as  represented  in 
Fig.  115,  until  the  required  form  and 
fullness  are  obtained,  adding  wax,  if 
necessary,  to  the  palatal  portion  of 
the  plate,  making  it  just  enough  thicker 
than  that  required  in  the  completed 
set  to  compensate  for  waste  in  the 
process  of  final  finishing.  Any  con- 
siderable excess  of  material  should  be 
avoided,  since  it  will  not  only  mate- 
rially increase  the  labor  of  dressing 
the  vulcanized  plate,  but  tend  to  in- 
duce porosity  or  sponginess  of  the  rub- 
ber under  heat.  A  rim  of  wax  should 
also  be  extended  around  the  front  and 
lateral  borders  of  the  plate,  overlapping 
somewhat  the  extremities  of  the  gum 
portions  of  the  teeth.  Wax  used  for 
the  purposes  indicated  should  be  of  the 
cleanest    and    purest    varieties.     A    set 


Fig.  115. 


288 


MECHANICAL   DENTISTRY, 


modeled  in  the  manner  described  will  present  the  appearance  rep- 
resented in  Fig.  116. 

Flasking. — The  process  having  been  conducted  thus  far — any 
defects  in  the  arrangement  of  the  teeth  having  been  previously 
corrected  upon  trial  of  the  plate  in  the  mouth — the  next  step  in  the 
operation  is  the  formation  of  a  mold  or  matrix  in  which  the  gum 
material  is  packed  and  pressed  preparatory  to  being  vulcanized. 
In  forming  a  matrix,  a  vulcanizing  flask  is  used,  the  forms  of 
which  are  separately  represented  in  Figs.  1 21-125.  The  lower 
section  of  the  flask  is  first  filled  one-half  or  two-thirds  full  of  plaster 
mixed  with  water  to  the  consistency  of  cream.     Into  this  the  base 

Fig.   116. 


of  the  model,  previously  moistened  with  water  (the  plate  and  teeth 
being  attached  to  the  model),  is  immersed  and  additional  portions 
of  the  plaster  added,  if  necessary,  filling  the  cup  even  with  the 
upper  edge,  and  extending  it  up  the  sides  of  the  model,  to  the  lower 
edge  of  the  external  rim  of  wax  attached  to  the  borders  of  the  gum 
plate.  The  base  of  the  model  should  be  cut  away,  so  that  when 
placed  in  the  flask  the  lower  edge  of  the  gum  plate  will  extend  but 
little  above  the  level  of  the  upper  borders  of  the  cup.  The  surface 
of  the  plaster  is  then  trimmed  smoothly,  and  coated  with  varnish 
and  then  oiled ;  all  the  exposed  portions  of  the  gum  plate  and  wax 
are  also  oiled,  leaving  the  surfaces  of  the  teeth  untouched.     The 


RUBBER  OR  VULCANITE  BASE.  289 

several  parts  will  now  present  the  appearance  represented  in  Fig. 
116.  The  upper  section  of  the  flask  is  next  placed  in  its  proper 
position  over  the  lower — the  slides  formed  in  one,  and  correspond- 
ing grooves  in  the  other,  determining  an  accurate  relation  of  the 
two  pieces.  Into  the  upper  rim  of  the  flask,  plaster,  mixed  to  the 
consistency  before  mentioned,  is  now  poured,  filling  it  completely. 
The  lid  or  cap  is  then  applied  to  the  opening  above,  and  the  several 
parts  of  the  flask  brought  firmly  together,  forcing  the  excess 
through  the  joints  of  the  flask.  As  soon  as  condensation  of  the 
plaster  takes  place,  the  flask  should  be  placed  in  a  hot-air  chamber 
or  on  a  stove,  and  heated  throughout  just  sufficiently  to  soften,  but 
not  melt  the  wax.  The  flask  should  be  heated  gradually,  otherwise 
the  contents  may  be  suddenly  and  forcibly  ejected,  in  consequence 
of  the  too  rapid  evolution  of  vapor.  The  two  sections  of  the  flask 
are  then  carefully  separated  by  forcing  the  blade  of  a  knife  or  a  small 
chisel-shaped  instrument  in  at  different  points  between  them,  the  lid 
closing  the  opening  above  remaining  in  place.  On  separating  the 
flask,  the  teeth,  with  the  wax  and  temporary  plate,  will  be  found 
attached  to  the  section  of  the  matrix  last  formed,  the  portions  of  the 
crowns  of  the  teeth  not  covered  with  wax  being  imbedded  in  the 
plaster  and  their  plate  extremities  presenting  toward  the  matrix,  as 
seen  in  Fig.  117.  The  base-plate  and  wax  should  now  be  carefully 
detached  with  such  instruments  as  will  best  enable  the  operator  to 
work  out  confined  portions  around  the  platinum  pins  and  from  the 
interstices  between  the  teeth,  being  careful  at  the  same  time  not  to 
deface  the  plaster  surface  of  the  mold.  To  relieve  the  matrix  more 
perfectly  of  all  traces  of  wax  not  accessible  to  instruments,  the 
section  containing  the  teeth  may  be  subjected  to  a  small  stream  of 
boiling  water,  which  should  be  dashed  upon  it  until  every  trace  of 
wax  is  removed. 

Before  packing  the  material,  provision  should  be  made  for  the 
escape  of  any  excess  when  the  matrix  is  filled  and  the  two  sections 
of  the  flask  are  forced  together,  permitting  the  latter  to  close  upon 
each  other  in  exactly  the  same  manner  as  before  the  introduction 
of  the  gum.  If  the  vulcanizable  substance  becomes  engaged  be- 
tween the  surfaces  of  the  plaster  around  the  matrix,  the  vulcan- 
ized base  will  be  increased  in  thickness  just  in  proportion  to  that  of 
the  interposed  layer  of  gum,  and  hence  the  teeth  of  replacement 
will  be  relatively  elongated.  This  increased  thickness  of  the  base 
19 


290 


MECHANICAL    DENTISTRY. 


and  consequent  changed  relation  of  the  teeth  to  the  maxillary  ridge 
and  to  those  of  the  opposing  jaw,  if  but  slight,  may  be  immaterial 
in  the  application  of  full  sets  of  teeth ;  but  it  is  far  different  in  the 
construction  of  partial  pieces,  where  the  perfection  of  the  finished 
work  depends  in  so  great  a  degree  upon  a  faultless  preservation  of 
the  exact  position  originally  assigned  to  the  organs  of  replacement 
in  the  several  vacuities  on  the  ridge.     If,  for  example,  in  replacing 

Fig.  117. 


the  superior  incisors,  the  approximation  of  the  two  sections  form- 
ing the  mold  is  obstructed  by  the  intrusion  of  the  gum  material 
between  the  plaster  surfaces,  the  teeth,  whether  plate  or  gum,  will 
be  relatively  elongated  in  proportion  to  the  increased  thickness  im- 
parted to  the  base  consequent  upon  the  incomplete  closure  of  the 
flask,  and  however  accurately  or  skilfully  the  porcelain  teeth  may 
have  been  originally  fitted  to  the  vacuity  in  front,  the  artificial  will 
be  found  to  depart  from  the  natural  gum,  while  the  porcelain  crowns 


RUBBER    OR    VULCANITE    BASE. 


29I 


will  be  displaced  and  projected  below  those  of  the  contiguous 
natural  organs.  Such  displacement  in  the  cases  last  referred  to, 
however  small  in  degree,  cannot  fail  either  to  impair  or  destroy  the 
value,  both  as  respects  appearance  and  utility,  of  the  substitute. 
The  method  of  furnishing  an  exit  to  redundant  material,  as  usually 
practised,  is  to  form  a  series  of  conduits  or  grooves  in  the  surface 
of  the  plaster,  extending  them  from  the  edge  of  the  matrix  to  the 
rim  of  the  cup.     The  escape  of  the  gum  will  be  facilitated  by  cutting 


Fig.   ii< 


notches  at  intervals  around  the  rim  of  the  flask,  making  the  grooves 
in  the  plaster  continuous  with  them,  the  grooves  being  about  Y\  of 
an  inch  apart.  To  still  more  effectually  prevent  the  intrusion  of 
the  vulcanite  material  between  the  surfaces  of  the  opposing  sections 
of  plaster,  a  circular  groove  may  be  cut  in  the  plaster  within  a  line 
or  two  of  the  margins  of  the  matrix,  as  is  shown  in  the  illustration, 
Fig.  118,  into  which  narrow  channels  at  short  distances  are  made, 
leading  from  the  mold ;  others,  again,  are  made  at  wider  intervals 


292 


MECHANICAL   DENTISTRY. 


from  the  circular  groove  to  the  outer  margins  of  the  flask,  termi- 
nating as  before  in  small  notches  found  in  the  rim  of  the  cup.  The 
two  pieces  when  closed  upon  each  other  form  a  matrix.  Into  the 
grooved  section  of  the  mold,  the  vulcanizable  substance  is  packed 
previous  to  being  indurated.  It  is  at  this  stage  that  the  materials 
employed  to  exclude  the  rubber  from  between  the  teeth,  and  noticed 
in  another  place,  are  packed  into  the  joints  before  the  gum  material 
is  introduced.  The  face  of  the  model  should  also  be  coated  with 
some  substance  which  will  prevent  the  rubber  from  penetrating  the 
pores  of  the  plaster  and  its  adhesion  to  the  surface  of  the  model. 
Preference  is  given  by  Professor  Wildman  to  liquid  silex,  as  being 
more  readily  detached  from  the  surface  in  finishing  than  the  prepa- 
rations mentioned.  Whatever  is  used,  it  should  be  allowed  to  dry 
perfectly  before  packing.  Other  methods,  and  good  ones,  are  to 
burnish  a  sheet  of  tin-foil  over  the  cast,  or  sprinkle  lycopodium 
or  soapstone  upon  the  surface  of  the  cast.     These  latter  should  be 

Fig.  119. 


brushed  off  with  a  jeweler's  brush  or  a  soft  brush  wheel,  which  will 
leave  the  surface  of  the  model  with  a  high  polish. 

Packing  the  Mold. — The  portion  of  the  flask  containing  the 
teeth  should  be  first  heated  in  an  oven  or  furnace,  or  over  the  flame 
of  a  spirit-lamp,  until  the  temperature  of  the  whole  is  sufficient  to 
render  the  rubber  soft  and  pliable  as  successive  portions  are  ap- 
plied and  pressed  into  the  mold,  and  to  retain  it  in  that  condition 
until  the  operation  of. packing  is  completed.  Narrow  strips  of  the 
rubber  should  first  be  worked  carefully  into  the  contracted  groove 
underneath  the  platinum  pins  with  small  curved  or  straight- 
pointed  spear-shaped  steel  instruments  (Fig.  119),  adding  on  small 
pieces  at  a  time  after  each  successive  portion  is  thoroughly  im- 
pacted, until  the  main  groove  of  the  matrix  over  the  base  of  the 
teeth  is  partially  filled.  The  palatal  convexity  of  the  mold  may 
tli en  be  covered  with  a  single  piece  cut  to  the  form  of  the  uncov- 
ered space;  a  smaller  piece  of  the  same  general  form  as  the  latter 
may  then  be  added,  giving  to  the  central  portion  a  double  thick- 
ii'  ;s  of  the  gum-plate  material,  so  that  when  the  two  sections  of 


RUBBER  OR  VULCANITE  BASE. 


293 


the  flask  are  brought  together,  the  excess  of  gum  in  the  center  will 
be  forced  gradually  to  the  margins  of  the  mold,  diminishing, 
thereby,  the  liability  of  the  grooves  becoming  prematurely  clogged 
with  the  material  before  the  opposing  sections  of  the  flask  close 
upon  each  other.  Especial  care  should  be  taken  in  the  process  of 
packing  to  avoid  contact  of  the  instruments  with  the  surface  of  the 

Fig.   120. 


mold,  as  fragments  of  the  broken  plaster  are  liable  to  mix  with  the 
gum  and  render  the  surface  of  the  finished  work  imperfect  by 
forming  small  pits  wherever  such  particles  occur. 

In  regard  to  the  quantity  of  rubber  necessary  perfectly  to  fill 
the  matrix,  experience  in  its  use  will  enable  the  operator  to  esti- 
mate   the    capacity    of    the    mold    with    tolerable    accuracy.     Some 


294  MECHANICAL    DENTISTRY. 

Small  excess  of  rubber  should  always  be  provided.  The  required 
quantity,  however,  can  be  more  certainly  determined  by  measure- 
ment. A  very  simple  instrument  (Fig.  120),  contrived  by  Dr.  E. 
T.  Starr,  may  be  used  to  determine  the  quantity  by  measurement. 
The  vessel  being  partly  filled  with  water,  the  lower  point  is 
adjusted  and  fixed  with  a  screw  to  mark  its  height.  Into  this 
every  particle  of  the  trial  base-plate  is  immersed,  and  the  rise  of 
water  indicated  in  the  same  manner  by  the  upper  point.  The 
vessel  is  then  emptied  and  well  cleansed,  clean  water  filled  in  to 
the  level  of  the  lower  point,  when  rubber  is  added  in  sufficient 
quantity  to  bring  the  surface  of  the  water  on  a  level  with  the  upper 
point ;  to  this  is  to  be  added  the  necessary  excess  of  rubber  before 
recommended. 

Having  completed  the  packing  of  the  mold,  the  two  portions  of 
the  flask  are  reapplied  to  each  other  in  exactly  their  original  rela- 
tion, being  careful  that  the  apposition  of  the  two  is  such  that,  when 
approximated,  the  guides  attached  to  one  division  of  the  flask  shall 
pass  directly  and  without  obstruction  into  the  grooves  or  slots  in 
the  one  opposite.  With  the  flasks  first  introduced,  some  difficulty 
and  uncertainty  were  experienced  in  effecting  the  desired  closure  of 
the  flask  on  account  of  inherent  defects  of  construction,  but  more 
recent  improvements  have  entirely  obviated  this  difficulty. 

What  is  known  as  the  "  Starr  Flask,"  highly  commended  as  ful- 
filling very  perfectly  the  requirements  of  practice,  and  as  happily 
meeting  some  important  indications,  is  represented  in  Fig.  121. 
Every  operator  of  experience  is  familiar  with  the  annoyance  and 
difficulty  sometimes  attending  a  satisfactory  adjustment  of  models 
of  unusual  depth,  often  of  lower  sets,  and  partial  pieces,  where  the 
porcelain  teeth  are  secured  by  the  surrounding  plaster  to  the  model 
— difficulties  arising  from  the  shallowness  of  the  lower  section  of 
flasks  as  ordinarily  constructed.  The  "  Reversible  Flask,"  invented 
by  Dr.  E.  T.  Starr,  the  different  parts  of  which  are  represented  in 
the  accompanying  cut,  provides  very  perfectly  for  any  exigency  that 
may  arise  in  the  class  of  cases  mentioned.  The  following  descrip- 
tion of  this  flask  is  taken  from  the  Dental  Cosmos: 

'The  rings  are  of  different  widths,  either  of  them  fitting  the  top 
or  bottom  accurately,  as  may  be  required. 

"  By  using  the  wide  ring  next  to  the  bottom,  an  admirable  flask- 
is  obtained   for  dec])  cases  and  partial   sets,  or  where  the  artificial 


RUBBER  OR  VULCANITE  BASE. 


295 


gum  rests  on  the  natural.     The  narrow  ring  is  used  next  the  bottom 

plate,  for  whole  dentures,  where  the  parting  is  at  the  rim  of  the 

plate.     The  bottom  has  three  countersunk  holes,  through  which  the 

plaster  runs,  and,  when  set,  holds  the  accompanying  ring  securely 

to  it.     The  fastenings  of  the  flask  are  T-shaped  at  one  end,  and  fit 

the  slots  in  the  bottom  plate ;  and,  being  free  at  both  ends,  are  more 

easily  adjusted  than  ordinary  bolts.     The  flask  being  in  four  pieces 

(two  rings  and  two  plates),  the  plaster  is  removed  without  the  usual 

trouble." 

Fig.   i2i. 


The  writer  has,  for  several  years,  used  with  much  satisfaction  a 
flask  constructed  with  detached  T-shaped  bolts  fitting  accurately 
into  slots  or  grooves  extending  continuously  from  top  to  bottom  of 
the  flask,  as  represented  in  Fig.  122.  The  closure  of  the  sections 
bv  this  arrangement,  with  the  bolts  in  place,  is  unerring,  and  is 
accomplished  with  the  greatest  facility.  It  is  known  as  the  "  Im- 
proved Anchor  Flask."  Another  useful  form  of  flask  is  that  de- 
vised by  Dr.  I.  N.  Broomell,  and  is  represented  in  Fig.  123. 

Fig.    124   represents    an    oblong,    or   "  box   flask,"    designed    for 


296 


MECHANICAL   DENTISTRY. 
Fig.  122. 


RUBBER  OR  VULCANITE  BASE. 


297 


exceptionally    large    cases,    splints    for    fractures,    artificial    palates, 
etc. 

Whatever  flask  is  used,  the  entire  mass  of  inclosed  rubber  should 
be  rendered  uniformly  plastic,  after  packing,  by  subjecting  it  to 
either  a  dry  heat,  such  as  may  be  obtained  with  a  conveniently  con- 
structed sheet-iron  furnace,  the  baking  apartment  of  an  ordinary 
cooking  stove,  or  any  other  available  means  by  which  a  diffused  and 
uniform  temperature  may  be  secured,  being  careful  not  to  overheat; 
or,  if  moist  heat  is  employed,  by  immersing  the  flask  in  boiling 

Fig.  125. 


water  for  a  time  sufficient  to  soften  the  rubber.  The  approximation 
of  the  sections  of  the  flask  should  be  effected  interruptedly — alter- 
nately heating  the  entire  mass  and  tightening  by  means  of  the 
screw-bolts  until  all  the  redundant  material  is  expelled  by  degrees 
through  the  outlets  provided  for  it,  and  the  sections  of  the  flask 
close  accurately  upon  each  other. 

The  Brown  Clamp  Flask. — This  simple  and  effective  appliance, 
devised  by  Dr.  Wister  P.  Brown,  is  intended  principally  to  do 
away  with  all  bolts,  and  to  give  a  more  even  and  ready  distribution 
of  pressure  in  closing  the  flask.     With  three  screws  we  may  move 


298  MECHANICAL    DENTISTRY. 

the  rubber  to  any  portion  of  the  flask  desired,  which  is  impossible 
with  a  one-screw  flask-press.  If  more  space  is  desired  between 
flask  and  clamp,  the  top  plate  of  flask  may  be  removed  and  turned 
bottom  upward,  when  the  flat  surface  of  the  clamp  bottom  will 
answer  same  as  top  plate.  Fig.  125  illustrates  this  form  of  flask. 
The  holder  (a),  key  (b),  and  a  brass  wire  lifter  (c),  prevent  any 
burning  or  soiling  of  hands.  Clamps  and  flasks  are  made  all  sizes, 
so  that  two  of  each  may  go  in  any  two-flask  vulcanizer.  If  the 
screws  of  the  clamp  are  kept  lubricated  with  oil,  they  will  last  for 
many  years. 

Vulcanizing. —  The  process  of  vulcanizing  or  hardening  the 
various  rubber  compounds  employed  for  dental  purposes  is  effected 
by  subjecting  them  for  variable  periods  of  time  to  the  action  of 
heat,  the  substances  to  be  acted  on  being  confined  within  a  chamber 
constructed  for  the  purpose. 

As  introductory  to  a  consideration  of  the  usual  methods  and 
appliances  employed  in  the  process  of  vulcanizing,  considerable 
space  is  given  to  the  following  abstract  of  a  paper  by  F.  Alb.  Boeck, 
of  Berlin,  Germany,  translated  by  Dr.  Louis  Ottofy,  of  Chicago. 
The  discussion  embodies  a  somewhat  exhaustive  consideration  of 
the  rationale  of  the  process  of  vulcanizing,  and  is  introduced  in  this 
connection  not  only  as  a  matter  of  curious  scientific  interest,  but  as 
of  practical  importance  in  the  proper  treatment  of  a  plastic  material 
which  still  continues  to  be  largely  used  as  a  base  for  artificial  den- 
tures.    The  writer  says : 

"  The  rubber  we  use,  as  is  well  known,  is  common  rubber  mixed 
with  sulphur,  to  which  is  added  certain  coloring  materials.  Of  the 
latter  I  will  speak  later  in  the  course  of  this  paper.  Though  they 
may  influence  the  hardening  of  the  rubber  indirectly,  they  have 
no  other  direct  influence.  This  rubber  mixed  with  sulphur  forms 
our  '  dental  rubber.'  The  rubber  which  we  obtain  from  the  dental 
depots  is  already  '  vulcanized,'  as  this  latter  simply  means  mixing 
the  sulphur.  We  know  that  when  it  is  heated  it  becomes  hard. 
The  circumstances  under  which  this  takes  place  leads  us  to  several 
questions:  Is  it  the  heat,  or  the  steam  pressure,  or  the  melting  of 
the  sulphur,  which  causes  the  change  in  the  rubber? 

"  Konnerly,  the  impression  prevailed  that  the  hardening  took 
place  from  the  influence  of  the  steam.  In  the  first  vulcanizers 
the  flask  stood  on  a  stand  in  the  vulcanizers  above  the  water;  but 


RUBBER  OR  VULCANITE  BASE. 


299 


as  once,  in  1856,  the  flask  fell  into  the  water,  the  vulcanizing  took 
place  as  usual,  the  mistake  was  corrected.  Later  it  was  found  that 
the  process  would  take  place  even  if  the  heat  was  passed  through 
oil  or  sand,  and  that  the  same  was  the  case  with  glycerin  and  par- 
affin. Certainly,  under  these  circumstances,  the  time  of  vulcanizing 
was  longer  than  when  steam  was  used ;  this  circumstance,  at  that 
time,  however,  was  of  no  particular  consequence,  as  it  took  from 
three  to  four  hours  to  vulcanize  it  by  steam.  I  will  return  to  this 
difference  of  time  later ;  suffice  it  to  state  here  that  vulcanizing  can 
take  place  in  the  absence  of  steam. 

"  It  is  clear,  therefore,  that  it  is  the  heat  alone  which  causes  the 
hardening  of  the  rubber.  In  order  to  answer  the  question  of  why 
this  takes  place,  it  will  be  necessary  to  turn  into  the  domain  of 
chemistry. 

"  The  rubber  is  a  vegetable  product ;  it  is  the  sap  of  certain  trees, 
which  hardens  on  exposure  to  the  air.  As  a  vegetable  product  it 
is  liable  to  the  changes  of  all  other  vegetable  substances,  and  all 
changes  which  it  undergoes  are  found  equally  effective  on  other 
vegetable  substances.  From  this  fact  it  is  very  simple  to  draw  con- 
clusions for  our  purpose. 

"  Chemistry  teaches  that  all  vegetable  products,  such  as  wood, 
starch,  the  leaves  and  sap  of  plants,  consist  of  four  elements, 
oxygen,  nitrogen,  hydrogen,  and  carbon.  In  no  plant,  or  the 
product  of  a  plant,  is  carbon  absent,  and  it  is  mostly  in  connection 
with  hydrogen  and  oxygen,  whereas  nitrogen  is  but  seldom  present. 
From  these  few  elements  nature  has  produced  all  that  earth  pos- 
sesses of  vegetable  growth,  the  variety  and  difference  being  some- 
times only  the  different  proportion  of  union  of  the  elements,  or  the 
addition  of  a  small  amount  of  acids,  bitter  substances,  coloring 
matters,  or  salts.  Rubber  consists  only  of  the  above  elements, 
namely,  C16H7 ;  it  belongs,  therefore,  to  the  class  known  as  the 
hydrocarbons,  and  to  that  class  of  these  in  which  C  predominates. 
It  is  interesting  to  notice  here  that  the  change  from  the  soft  to  the 
hard,  as  is  the  case  with  rubber,  is  the  property  of  all  vegetable 
products.  We  know  that  the  change  takes  place  by  the  application 
of  heat,  that  hydrogen  sulphid  (H2S)  is  formed,  and  that  the  proc- 
ess takes  place  during  the  exclusion  of  air.  This  process  is  chem- 
ically the  same  as  takes  place  in  the  dry  distillation  of  wood,  in  the 
changing  of  wood  into  coal,  and  of  resin  into  amber.     If  wood  is 


300 


MECHANICAL   DENTISTRY. 


heated  in  the  open  air  it  burns;  the  same  is  the  case  with  rubber, 
only  that  the  latter  bums  slower  on  account  of  its  larger  percentage 
of  C.  If  wood  is,  however,  heated  in  the  absence  of  air,  as  is  the 
case  in  making  illuminating  gas,  quite  peculiar  substances  are 
eliminated  from  the  wood,  the  illuminating  gas,  which  escapes,  and 
three  substances;  a  watery  pyroligneous  acid  (wood-vinegar),  a 
thick,  viscid  liquid  (wood-tar),  and  a  solid  mass  (charcoal). 

"  The  wood-tar  is,  like  the  rubber,  of  a  resinous  nature ;  it  con- 
sists of  the  oil  of  wood-tar  and  a  liquid  substance,  burnt  resin. 
Both  become  hard  on  cooling;  the  former  is  the  well-known  paraffin, 
the  latter  the  equally  well-known  pitch. 

"  The  rubber  undergoes  similar  changes.  If  it  is  heated  while 
excluded  from  the  air,  as  is  the  case  in  vulcanizing,  there  escapes 
(as  in  the  case  of  wood,  illuminating  gas),  the  hydrogen  sulphid, 
and  there  remains  a  plastic,  which  hardens  on  cooling,  as  in  the 
case  of  pitch  or  paraffin,  and  we  have  our  hard  rubber. 

"  If  we  think  over  this  subject,  it  becomes  clear  to  us  why 
sulphur  is  added  to  the  rubber.  By  dry  distillation  one  or  more 
equivalents  of  hydrogen  separate  from  the  mass  and  remain  gaseous, 
or  unite  with  other  substances  present  and  form  a  liquid,  thus 
leaving  behind  a  hard  substance,  which  consists  mainly  of  C.  It 
is  well  known  that  the  hardest  substance,  the  diamond,  is  pure  C. 
The  more  equivalents  of  H  that  remain,  the  softer  is  the  substance, 
as  in  the  following  scale :  coal,  resin,  pitch,  axle  grease,  oil,  ethereal 
oils,  gases.  The  same  is  the  case  in  the  reversed  order.  If  from 
the  soft  rubber  hard  rubber  is  to  be  made,  it  is  necessary  to  remove 
from  it  one  or  more  equivalents  of  H.  This  is  the  case  in  dry  dis- 
tillation. If  there  was  no  dry  distillation,  if  the  rubber  was  heated 
under  free  admission  of  air,  the  C  would  immediately  unite  with 
the  O  of  the  air,  forming  carbonic  acid,  combustion  would  take 
place,  even  though  it  would  be  slow  and  difficult.  That  cannot 
take  place  when  the  air  is  excluded,  the  carbon  remains  unchanged, 
whereas  the  H  finds  a  substance  with  which  it  is  more  than  willing 
to  unite  at  a  high  temperature.  This  substance  is  the  S,  and  the 
union  of  these  forms  H2S,  which  is  well  known  to  us  by  its  odor. 
When  this  union  has  taken  place  a  chemical  change  has  been 
accomplished,  a  new  substance  has  been  produced,  the  gas  escapes, 
the  remainder,  the  product  of  the  distillation,  contains  less  H  than 
the  raw   rubber,  and  on  cooling,  like  pitch,   it  becomes  a  harder 


RUBBER  OR  VULCANITE  BASE.         ;       3OI 

substance  by  its  containing  more  C  than  before.  Hard  rubber, 
therefore,  is  one  step  nearer  to  resin  than  soft  rubber.  All  resins 
are,  as  is  well  known,  involatile  substances,  and  they  possess  the 
power  to  prevent  other  substances  from  becoming  volatile;  they 
are  insoluble  in  water,  and,  consequently,  tasteless;  they  are  soluble 
in  volatile  oils,  as  turpentine  oil,  benzene,  etc.  It  is  known  that 
hard  rubber  does  not  only  possess  these  characteristics,  but  resem- 
bles the  resins,  by  its  easy  electrification,  to  a  remarkable  degree. 

"  My  hypothesis,  therefore,  leads  me  to  the  following  conclusion : 

"  The  hardening,  or  so-called  vulcanising  of  rubber,  is  the  changing 
of  caoutchouc  into  a  resin-resembling  substance,  by  the  process  of  dry 
distillation;  that  is,  by  the  removal  of  one  equivalent  of  H.  The 
addition  of  S  serves  only  as  a  base,  which  is  indifferent  toward  C,  but 
unites  with  H  by  virtue  of  a  strong  chemical  affinity  existing  between 
H  and  S,  which  form  a  new  compound,  H2S,  which  escapes  as  a  gas. 

"  You  will  notice  I  do  not  agree  with  the  opinion  that  the 
sulphur,  by  melting  and  hardening,  exerts  the  influence  required 
to  harden  the  rubber.  The  hypothesis  was  laid  down  in  some 
American  dental  journal,  that  just  as  is  the  case  with  camphor 
and  celluloid,  it  is  with  sulphur  and  rubber;  that  is,  that  the 
sulphur  is  the  medium  which  brings  the  particles  of  rubber  into 
the  plastic  condition,  and  afterward  retains  them  in  the  hardened 
condition. 

"  We  know  that  a  portion  of  the  original  composition  of  the 
rubber  has  disappeared,  and  we  know  that  some  of  the  sulphur 
and  hydrogen  disappear.  It  is  natural  that  if  more  sulphur  is 
present  than  can  combine  with  one  equivalent  of  hydrogen,  the 
remainder  is  in  mechanical  union  with  the  rubber.  If  hard  rubber 
be  heated  to  a  degree  somewhat  higher  than  the  boiling-point  of 
water,  it  loses  its  hardness.  This  fact  might  lead  to  the  conclusion 
that  the  sulphur  melts,  and  thus  influences  the  hardness  of  the 
rubber.  If,  however,  the  correctness  of  my  theory  be  granted — 
that  is,  that  hard  rubber  is  nothing  but  the  resinous  state  of  the 
original  product — we  observe  that  it  must  soften,  as  the  melting- 
point  of  the  resins  is  about  the  same  as  that  of  sulphur.  Further- 
more, we  know  that  sulphur  hardens  slowly,  whereas  resins  become 
hard  more  rapidly,  as  is  the  case  with  shellac  and  sealing-wax; 
the  same  is  the  case  with  heated  hard  rubber.  Hard  rubber,  when 
undergoing  the   change   from   its   melted   condition   into   the   hard 


302 


MECHANICAL   DENTISTRY. 


condition,  does  not  change  the  character  of  its  molecular  relation,, 
remaining  amorphous ;  resembling  in  its  structural  appearance 
molten  glass.  All  resins,  gum,  glue,  tar,  etc.,  show  the  same  char- 
acteristics. Sulphur,  on  the  contrary,  when  changing  from  its 
molten  condition,  either  crystallizes  or  becomes  crystalline  in  ap- 
pearance. 

"  I  do  not  wish  to  prove  anything  further  by  this  theory.  It 
may,  however,  be  mentioned,  that  if  it  be  correct,  some  important 
results  may  be  accomplished.  I  will  mention,  for  one,  the  fact 
that  the  scraps  and  filings  of  hard  rubber,  which  are  now  useless 
and  thrown  away,  may  be  made  valuable  and  useful.  Lately,  a 
patent  has  been  obtained  by  which  useless  vulcanized  rubber  may 
be  made  useful. 

"  Leaving  this  subject,  we  now  arrive  at  one  not  less  important, 
namely,  the  influence  of  steam  pressure  on  vulcanization. 

"  It  has  been  previously  stated  that  vulcanized  rubber  may  be 
hardened  without  steam.  This  teaches  us  that  hardening  is  not 
produced  by  steam.  The  theory  which  has  been  discussed  gives 
us  the  reason.  The  question  arises,  why  do  we  use  steam?  The 
answer  is,  steam  has  no  direct  influence  in  vulcanizing;  it  only  serves, 
the  same  as  oil,  sand,  paraffin,  or  glycerin,  for  the  transmission  of 
the  heat.  This  takes  place  by  use  of  steam,  faster  and  with  more 
precision  and  certainty  than  with  other  substances.  Furthermore, 
it  will  be  shown  further  on  that  for  other  reasons  steam  is  the  best 
vehicle  for  the  purpose. 

"  As  with  oil,  by  using  steam  the  heat  is  equally  distributed 
and  the  temperature  rises  evenly.  Changes  of  temperature,  as  is 
the  case  in  dry  vulcanization  or  overheated  steam,  are  also  pre- 
vented. It  also  has  the  important  advantage  of  causing  the 
hardening  to  take  place  more  rapidly.  This  latter  fact  is  known 
to  us  by  experience ;  it  only  remains  to  explain  the  reason  why 
this  is  so. 

"  By  the  use  of  steam,  hardening  takes  place  in  from  fifteen  to 
seventy-five  minutes,  according  to  the  temperature,  the  quality  of 
the  rubber  and  its  thickness ;  by  the  use  of  dry  heat  or  oil  the 
process  requires  from  two  to  three  hours,  and  the  requisite  degree 
of  heat  must  be  reached  gradually.  What  is  the  reason  that  by 
use  of  steam  and  a  high  degree  of  heat  it  takes  less  time  to 
vulcanize?     It  must  he  remembered  that  the  higher  the  tempera- 


RUBBER  OR  VULCANITE  BASE. 


303 


ture,  the  less  time  is  required  to  vulcanize.  The  reason  of  this  is 
clear,  if  we  remember  that,  according  to  my  theory,  hardening  is 
subservient  to  the  escape  of  a  certain  amount  of  hydrogen  from  the 
rubber. 

"  The  greater  the  heat,  the  easier  is  the  separation  of  the  un- 
natural union,  as  it  were,  of  the  hydrogen  with  the  carbon  of 
the  rubber,  and  it  also  facilitates  the  union  of  this  H  with  the  S, 
which  is  in  a  molten  condition.  This  takes  place  in  accordance 
with  the  laws  of  chemical  affinity  and  relation.  It  is  a  sort  of 
magnetic  power  which  the  sulphur  exerts  upon  the  hydrogen,  and 
which  becomes  firmer  and  more  powerful  the  higher  the  tempera- 
ture. Here  the  steam  does  not  take  any  part,  as  it  only  does  the 
same  thing  that  oil  or  sand  would  do,  and  that  is  to  transmit  the 
heat.  There  must  be  another  reason  why  the  use  of  steam  per- 
mits us  to  increase  the  temperature  and  shorten  the  time.  We 
know  that  we  cannot  do  so  when  using  sand  or  oil,  as  in  that  case 
the  rubber  becomes  porous.  If  we  can  find  the  reason  why  the 
rubber  becomes  porous,  we  can  ascertain  the  influence  of  the  steam 
when  used  a  shorter  time. 

"  A  great  deal  has  been  written  and  said  in  regard  to  the  poros- 
ity of  rubber.  This  takes  place  when  the  escape  of  the  gas  is  re- 
tarded or  prevented  in  certain  places.  This  may  take  place  when 
the  heat  was  applied  rapidly  or  unevenly,  or  when  it  was  not  equally 
distributed  to  all  parts  of  the  rubber.  In  the  latter  case,  such 
parts  as  are  more  exposed  to  the  radiating  heat  than  others  become 
hard  much  sooner,  because  the  H  escapes  quicker.  In  the  former 
case,  that  is,  by  rapid  increase  of  heat,  the  outer  surface  of  the 
rubber  hardens  sooner  than  the  inner,  to  which  the  heat  only 
reaches  gradually.  Rubber  is,  as  is  well  known,  the  poorest  of 
conductors.  It  is  clear,  therefore,  that  the  thicker  a  piece  is,  the 
longer  it  takes  it  to  become  heated  in  all  parts,  and  the  more 
gradual  must  be  the  heating,  in  order  that  an  even  hardening,  or 
rather  an  even  drying,  of  the  mass  may  take  place,  so  as  not  to 
produce  a  hardened  outer  rim  when  the  inner  substance  is  yet  soft, 
i.  c,  contains  more  H.  The  H,  which  is  becoming  rarefied  by  the 
increase  of  heat,  has  not  the  power  to  force  itself  through  the 
hardened  parts ;  it,  however,  possesses  a  considerable  power  of  ex- 
pansion,  which   increases   by   the   constant   application   of   heat ;   it 


304 


MECHANICAL   DENTISTRY. 


therefore  forms  a  cavity  for  itself  in  which  the  yet  unhardened 
rubber  deposits  its  H  as  long  as  it  escapes  from  the  rubber,  and 
until  it  is  free  from  it  and  becomes  hard.  This  is  a  supposition 
which  becomes  more  clear  by  future  statements. 

"  Accordingly,  in  order  to  prevent  porosity,  nothing  else  is  neces- 
sary than  to  heat  it  in  such  a  manner  that  the  heat  is  equally  dis- 
tributed.    This  result  is  obtained  by  observing : 

"  i.  That  the  heat  is  equal  on  all  surfaces,  and 

"  2.  That  the  heat  be  gradually  raised  and  continued,  according 
to  the  thickness  of  the  plate. 

"  In  making  plates  of  considerable  thickness,  experience  taught 
us  to  observe  the  above  rules,  or  the  strength  would  be  lessened. 

"  It  was  mentioned  before  that  steam,  like  oil  or  paraffin,  serves 
simply  to  convey  the  heat.  It  furthermore  possesses  two  other 
properties  which  make  it  more  valuable  than  the  other  substances : 
i.  Its  well-known  property  of  conducting  heat.  2.  Its  elasticity. 
In  consequence  of  its  conductibility,  it  distributes  the  heat  evenly; 
and  in  consequence  of  its  elasticity,  it  prevents  an  uneven  rise  of 
its  temperature,  while  oil,  e.  g.,  will  follow  any  change  in  the  tem- 
perature that  may  be  caused  by  the  applied  heat.  Consequently, 
steam  serves  as  a  reservoir  of  heat,  as  a  balance-wheel  serves  as  a 
reservoir  of  power;  as  the  latter  distributes  the  force,  so  does  steam 
distribute  evenly  the  over-abundance  of  heat  from  one  point  where 
the  flame  is  larger,  or  for  a  moment  when  the  heat  is  greater  it  is 
equalized  over  the  surface  and  over  several  minutes  of  time.  There- 
fore, if  the  rubber  exposed  to  it  is  not  too  thick,  so  that  its  influence 
can  reach  through  the  whole  mass  of  the  poorly  conducting  rubber, 
one  may  be  certain  that  by  the  use  of  steam  the  heat  exerts  its  in- 
fluence evenly  and  the  temperature  also  rises  equally.  There  need 
be  no  fear,  therefore,  that  one  place  will  be  harder  than  another,  as 
is  often  the  case  with  oil;  also  the  temperature  may  be  raised 
higher,  and,  consequently,  less  time  required  for  the  process,  and  no 
fear  entertained  on  account  of  porosity. 

"  Another  property  of  steam  may  here  be  considered  which 
exerts  a  still  greater  influence  than  cither  its  conductibility  or 
elasticity,  and  which  also  hastens  the  process  I  have  illustrated, 
chemical  affinity;  viz.,  the  magnetic — that  is,  the  power  of  sub- 
stances to  form  certain  compounds. 


RUBBER  OR  VULCANITE  BASE. 


305 


"  The  steam  acts  like  a  magnet  upon  the  sulphureted  hydrogen, 
dissolving  this  gas  with  a  great  deal  of  alacrity,  forming  a  solution 
of  sulphureted  hydrogen. 

"  It  is  true  that  the  property  of  steam  is  contradictory  to  the 
formation  of  H2S  within  the  rubber.  The  hardening,  in  my  opinion, 
is  nothing  more  than  dry  distillation,  and  this  is  nothing  more 
than  '  slow  burning  by  the  exclusion  of  air.'  This  takes  place  more 
rapidly  the  better  the  provisions  are  for  carrying  away  the  products 
of  combustion,  such  as  carbonic  acid,  oxid  of  carbon,  etc.,  and  the 
same  is  the  case  in  any  chemical  change. 

"  What  the  chimney  is  in  the  burning  of  wood,  the  steam  is  in 
vulcanization.  In  the  latter,  the  product — that  is,  the  H2S — is 
readily  taken  up  by  the  steam,  thus  furnishing  the  opportunity  for 
more  to  be  formed,  and  permitting  the  rubber  to  harden  quickly. 
This  is  the  main  reason  why  we  can  vulcanize  faster  when  using 
steam  than  either  oil  or  sand. 

"  The  other  properties  of  steam  permit  of  raising  the  temperature 
rapidly,  and  by  absorbing  the  gas  which  is  formed,  serve  as  a  proof 
of  the  foregoing  assertion,  that  the  hardening  of  rubber  takes  place 
by  the  escape  of  one  equivalent  of  H2,  and  that  porosity  is  caused 
by  hindering  the  escape  of  this  gas." 

The  Time  and  Temperature  Necessary. — As  solid  fuel  is  no 
longer  employed  in  vulcanizing,  any  description  of  the  apparatus 
especially  adapted  to  this  mode  of  producing  heat  is  deemed  un- 
necessary. They  have  been  entirely  superseded  by  others  of 
improved  form  and  construction  adapted  to  the  use  of  either  gas, 
alcohol,  or  coal-oil  and  its  products,  for  heating  purposes.  After 
the  lamp  or  burner  has  been  lighted,  it  should  be  so  regulated  as 
to  require  a  half  hour  to  raise  the  temperature  to  the  vulcanizing- 
point,  3200  F.,  or  120  lbs.  pressure  by  steam-gage.  This,  of  course, 
is  for  ordinary  work;  where  for  any  reason  the  rubber  is  unusually 
thick  the  time  for  running  it  up  to  the  vulcanizing-point  should  be 
extended  to  one  hour  or  more,  according  to  the  thickness  of  the 
mass,  as  the  heat,  if  run  up  too  rapidly,  will  cause  the  rubber  to 
become  spongy  or  porous. 

Fig.  117  represents  the  Hayes  vulcanizer  with  capacity  for  from 
one  to  three  cases.  The  iron-clad  improvement  in  these  machines 
is  designed  as  a  protection,  from  the  dangers  of  explosion  conse- 
quent upon  a  gradual  thinning  of  the  copper  boiler  from  corrosion, 


;o6 


MECHANICAL   DENTISTRY. 


a  safeguard  of  great  practical  value  and  concern  to  those  who  are 
continually  exposed  to  the  perils  of  such  an  accident.  The  shell 
is  made  of  malleable  iron,  }£  of  an  inch  thick,  strong  enough  to 
resist  many  times  the  strain  required,  and  can  never  be  exposed 
to  deterioration.  The  copper  lining  is  made  the  same  thickness  as 
the  copper  boilers  now  in  use,  and  the  machine  may  be  used  with 


Fig.  126. 


perfect  safety,  even  when  the  copper  has  become  as  thin  as  paper; 
and  then,  when  an  opening  has  been  fairly  eaten  through,  steam  will 
escape  from  between  it  and  the  iron  shell,  below  the  packing  joint, 
giving  timely  notice  that  a  new  lining  is  required,  which  can  be 
inserted  at  moderate  expense,  and  render  the  vessel  good,  and  safe 
as  new. 

A  peculiar  and  important  feature  of  these  vulcanizers  is  in  placing 


RUBBER  OR  VULCANITE  BASE.  3O7 

the  thermometer  bulb  within  a  mercury  bath,  outside  the  steam- 
chamber,  relieving  it  entirely  from  the  danger  of  being  crushed  or 
checked  by  the  pressure  of  steam,  as  is  liable  to  happen  when  it  is 
exposed  to  the  steam  itself,  necessitating  its  frequent  replacement. 

In  the  accompanying  illustration  the  time  and  gas  regulator  is 
also  shown.  This  regulator  (the  Coolidge-Lewis)  is  without  doubt 
the  most  convenient  and  perfect  in  its  action  and  adjustment  of  any 
yet  constructed. 

The  pointer  is  so  constructed  that  it  acts  as  a  stop  by  coming  in 
contact  with  the  inlet  tube.  This  stop  prevents  the  regulator  from 
being  set  either  by  design  or  accident  to  maintain  a  higher  tem- 
perature than  the  highest  graduation  on  the  base,  and  endangering 
the  safety  of  the  vulcanizer.  It  also  requires  no  special  adjustment 
after  leaving  the  factory. 

To  vulcanize  at  any  of  the  degrees  of  temperature  marked  on 
the  graduated  base,  all  that  is  required  is  to  turn  the  milled  hand- 
plate  till  the  pointer  is  over  the  degree  desired.  This  can  be  done 
either  before  or  after  lighting  the  gas  under  the  vulcanizer. 

It  should  not  be  forgotten  when  vulcanizing  at  a  low  heat  to 
extend  the  time  of  vulcanization. 

Better  results  are  obtained  by  running  the  vulcanizer  from  an 
hour  and  a  half  to  two  hours — exclusive  of  the  time  of  heating  up 
— at  a  low  heat. 

This  graduated  gas  regulator  is  provided  with  a  by-pass  screw 
adjustable  to  different  pressures  of  gas.  The  adjustment,  as  it 
leaves  the  factory,  is  for  coal  gas — low  pressure.  If  the  regulator 
is  to  be  used  with  natural  gas,  at  a  high  pressure,  too  much  gas 
will  be  passed  after  the  proper  temperature  has  been  reached.  A 
readjustment  of  the  by-pass  will  then  be  required.  This  is  accom- 
plished by  turning  the  small  screw  on  the  side  of  the  gas-chamber 
till  the  flame  maintains  the  heat  at  the  proper  temperature.  Fuller 
instructions  accompany  these  regulators  when  sold  to  the  profes- 
sion. 

The  Whitney  Vulcanizer. — A  not  less  convenient,  safe,  and 
reliable  vulcanizer  is  that  known  as  Dr.  Whitney's,  represented  in 
Fig.  127,  having  a  steam-chamber  capacity  for  from  one  to  three 
flasks. 

The  Mann  Vulcanizer  is  shown  in   Figs.   128  and   129.     The 


3o8 


MECHANICAL    DENTISTRY, 
Fig.   127. 


Fig.  128. 


Fig.  129. 


RUBBER  OR  VULCANITE  BASE. 


309 


same  apparatus  has  stove  attachment  for  the  use  of  kerosene,  and 
admits  of  the  use  of  thermometer  or  steam-gage. 

The.  facility  with  which  this  vulcanizer  may  be  operated  is  one 
of  its  distinctive  features.  The  lid,  instead  of  being  screwed  on  to 
the  boiler,  is  fitted  neatly,  and  rests  on  a  shoulder  formed  on  the 
casting,  and  is  secured  by  a  heavy  steel  clamping-bar  and  screw- 
bolt.  One  end  of  the  bar  is  hinged  to  the  side  of  the  boiler,  the 
outer  end  being  slotted  to  receive  the  screw-bolt,  which  is  hinged 
to  the  other  side  of  the  boiler.  Rubber  packing  between  the  lid 
and  the  shoulder  on  which  it  rests  makes  the  joint  steam-tight. 
The  lid  is  removed  by  unscrewing  the  nut  of  the  screw-bolt  a  turn 
or  two,  when  the  bolt  drops  out  of  the  slot  and  the  bar  is  turned 
back,  leaving  the  lid  free  to  be  removed.  This  method,  while  it 
gives  as  perfect  a  fastening  as  the  usual  plan,  affords  very  much 
greater  facility  for  opening  and  closing  the  boiler.  Should  it  stick, 
by  reason  of  the  packing  becoming  chilled  (a  common  occurrence 
with  all  vulcanizers),  it  is  pried  off  with  very  much  less  trouble  than 
is  required  when  the  top  screws  on. 

Another  advantage  is  the  bail,  a  simple  but  heretofore  un- 
thought-of  device,  which  greatly  facilitates  the  handling  of  the  vul- 
canizer, especially  when  hot.  Thus  the  boiler  can  be  opened  for 
the  removal  of  one  case  and  the  placing  of  another.  The  nut  of 
the  clamping-bolt  is  loosened  a  little  at  a  time,  allowing  the  steam 
to  escape  gradually  until  the  bolt  is  released,  when  the  bar  can  be 
thrown  back  and  the  top  of  the  boiler  raised.  The  bail  is  also 
useful  in  removing  the  boiler  from  the  jacket,  in  tightening  or 
loosening  the  screw-bolt  when  closing  or  opening  the  boiler,  and 
at  all  times  when  the  boiler  is  to  be  lifted.  When  not  in  use  it  is 
readily  removed. 

The  Boston  Vulcanizer. — This  vulcanizer,  manufactured  by 
the  Boston  Dental  Manufacturing  Co.,  is  made  of  the  best  bronze, 
so-called  "  gun-metal,"  and  is  tested  at  1000  pounds  hydraulic 
pressure.  It  will  hold  three  flasks,  and  allow  plenty  of  room 
for  handling.  The  packing  is  molded  instead  of  being  cut  in 
strips,  and  it  is  claimed  will  last  for  years  without  being  re- 
newed. The  cover  can  be  screwed  steam-tight  without  the  use 
of  a  wrench,  the  same  being  necessary  only  to  open  after  being 
heated.  The  small  quantity  of  water  used  (one  gill)  produces 
vulcanizing  by  steam,  instead  of  water,  thus  giving  better  results. 


3io 


MECHANICAL    DENTISTRY. 


The  bed-plate  jacket,  which  is  screwed  to  the  bench,  allows 
an  easy  and  ready  method  of  handling.  It  is  illustrated  in  Fig. 
130. 

The  Philadelphia  Vulcanizer. — The  several  parts  of  this  vul- 
canizer  are  illustrated  in  Fig.  131.  Its  simplicity  is  shown  in  a, 
b,   and   c.     a   represents   the   copper   bowl ;   b,   the   ring  or   socket 

Fig.  130. 


Wm<\ 


EMONT::- 

w.  >■? 

lite*'" 


with  an  annular  rib  on  the  top,  which  supports  the  copper  bowl, 
while  C  shows  the  tripod  yoke  or  lid.  There  are  no  bolts,  nuts, 
wrench,  nor  bed-plate  required,  making  it  altogether  the  simplest 
and  oii<-  of  the  most  convenient  vulcanizers  extant. 

In  vulcanizing,  the  heat  should   he  maintained  at  3200   for  about 
one  hour  and  ten  or  twenty  minutes.     Vulcanization  may  be  effected 


RUBBER  OR  VULCANITE  BASE. 


311 


at  a  lower  heat,  but  the  time  must  be  proportionately  extended; 
or  a  higher  heat  being  employed,  a  less  time  will  be  required 
to  vulcanize.  Care  should  be  taken,  however,  not  to  overheat, 
as  the  rubber  is  thereby  rendered  dark  and  brittle,  and  the 
important  property  of  elasticity  impaired.  The  time  and  degrees 
of  heat  mentioned,  therefore,  may  be  regarded  as  the  safest, 
and  as  yielding  the  best  results,  though  with  other  rubber  com- 
pounds, and  the  use  of  modified  forms  of  vulcanizers,  corre- 
sponding differences  in  time  and  temperature  may  be  required, 
and  which  can  only  be  accurately  determined  by  vulcanizing  test- 
pieces  of  rubber. 

In  this  connection  the  reader's  attention  is  called  to  some  practi- 
cal observations  on  the  subject  of  steam  pressure  in  vulcanizing, 


and  the  reliability  of  thermometers  as  indicators  of  heat,  and  which 
acquire  additional  interest  if  it  be  true,  as  alleged,  that  many  of  the 
vulcanizers  in  use  by  dentists  are  insecure  by  reason  of  inherent 
defects  of  construction  or  faultiness  in  the  modes  of  indicating  the 
elastic  force  of  steam.  In  commenting  on  this  subject  the  late  Prof. 
Wildman  observes : 

"  As  high  steam  is  used  in  vulcanizing,  it  is  important  that  the 
operator  should  be  conversant  with  the  nature  of  the  agent  which 
he  employs  to  accomplish  this  end.  It  is  perfectly  safe;  but  the 
following  will  show  him  that  it  must  be  used  with  discretion  and 
judgment.  Numerous  experiments  have  been  made  by  scientific 
men  to  ascertain  the  elastic  force  of  steam  at  different  temperatures. 
The  results  of  their  investigations  are  not  uniform,  although  they  all 
agree  in  showing  the  immense  force  exerted  bv  this  agent  at  high 


312 


MECHANICAL   DENTISTRY. 


temperatures.  HasweU's  tables  are  looked  upon  as  good  authority. 
The  results  of  the  investigations  of  the  Franklin  Institute  Com- 
mittee, in  the  higher  degrees,  give  a  greater  elastic  force  than  the 
table  below  quoted.  I  shall,  however,  quote  the  results  of  the  experi- 
ments of  the  commission  of  the  French  Academy,  appointed  by  the 
French  government  to  investigate  this  subject,  for  the  reasons  that, 
from  the  manner  in  which  they  were  conducted,  they  are  probably 
as  reliable  as  any,  and  that  they  are  extended  to  a  more  elevated 
temperature  than  the  others. 


Elasticity  of  steam,  taking 

Pressure,  per  square  inch, 

atmospheric  pressure  as  unity. 

Temperature  F. 

pounds. 

I 

212° 

14.7 

lV2 

233. 96° 

22.05 

2 

250.52° 

29.4 

2V2 

263.84° 

36.75 

3 

275.18° 

44.I 

lY* 

285.08° 

51-45 

4 

293.72° 

58.8 

4l/2 

300.28° 

66.15 

5 

307-050 

73-5 

SH        • 

314.24° 

80.85 

6 

320.36° 

88.2 

6y2 

326.26° 

95-55 

7 

331-70° 

102.9 

7Y2 

336.86° 

110.85 

8 

341-78° 

1 1 7.6 

9 

350.78° 

132.3 

10 

358.88° 

147 

ii 

366.85° 

161. 7 

12 

374.00° 

176.4 

13 

380.66° 

191.1 

14 

386.94° 

205.8 

15 

392.86° 

220.5 

16 

398-48° 

235-2 

17 

403.82° 

.  249-9 

18 

408.92° 

264.6 

19 

413-78° 

279-3 

20 

418.46° 

294 

"  I  would  here  call  the  attention  of  those  using  high  steam  to 
an  important  consideration.  In  raising  steam,  the  ratio  of  increase 
of  pressure  or  elastic  force  is  far  greater  than  that  of  the  increase  of 
temperature. 

"  By  referring  to  the  above  table,  commencing  at  2120  and  tak- 


RUBBER   OR   VULCANITE   BASE.  313 

ing  steps  as  near  500  as  is  given  in  the  ascending  scale,  we  find  this 
exemplified.     Thus : 

Increase  of  force  per         Giving  a  force  per 
Increase  of  temperature.  square  inch.  square  inch. 

From  2120        to  263.840  —  51.85°  22.05   lbs.  36.75   lbs. 

"      263.84°  to  314.24°  =  50.40°  44.10  lbs.  80.85   K>s. 

"   314.24°  to  366.85°  =:  52.61°  80.85  tt)S.         161.85  lbs. 

"   366.85°  to  418.46°  =  51.61°       132.15  lbs.       294    lbs. 

"  This  comparison  shows  clearly  how  rapidly  the  pressure  in- 
creases at  high  temperatures,  and  warns  the  operator  that  a  strong 
instrument,  combined  with  care  and  judgment  in  its  treatment,  are 
indispensable  to  safety.  Besides  the  rapid  increase  of  pressure,  it 
must  be  borne  in  mind  that  at  high  temperatures,  copper,  of  which 
the  boiler  is  composed,  becomes  weakened,  and  in  a  measure  loses 
its  power  to  resist  this  great  imprisoned  force.  Copper,  in  passing 
from  2120  to  2300  F.,  loses  about  one-tenth  of  its  strength,  and  at 
5500  it  has  lost  one-fourth  of  its  tenacity." 

In  a  paper  read  before  the  Massachusetts  Dental  Association, 
January,  1865,  Dr.  A.  Lawrence  affirms  that :  "  Most  vulcanizers 
are  now  made  of  sheet-copper  -i  of  an  inch  in  thickness,  and, 
agreeably  to  the  foregoing  facts,  have  a  tensile  strength  of  1875 
pounds ;  and  one  four  inches  in  diameter  will  not  sustain  a  pressure 
of  more  than    150  pounds  per   square  inch,   or   a   temperature   of 

363°- 

"  Let  us  next  ascertain  what  force  of  steam  is  exerted  upon  the 
boiler  within  a  short  range  of  temperatures.  We  find  by  the  tables 
of  Haswell,  King,  and  others,  that  at  3200  the  pressure  is  85 
pounds;  at  3240,  90  pounds;  at  328°,  95  pounds;  and  at  3320  it  is 
100  pounds  per  square  inch.  These  figures  I  have  verified  by  a 
steam-gage  connected  with  my  own  vulcanizer,  and  which  I  now 
use  in  preference  to  a  thermometer,  as  I  consider  it  more  convenient, 
safer,  and  less  liable  to  accidents. 

"  Practical  engineers  concur  in  the  opinion  that  a  force  of  not 
over  one-half  the  sustaining  capacity  of  the  boiler  can  be  safely 
applied." 

Thermometers  as  Indicators  of  Heat. — Immediately  connected 
with  the  process  of  vulcanizing  is  the  question  of  the  reliability 
of  thermometers  as  indicators  of  heat  or  steam  pressure.  Dr. 
Lawrence,  commenting  on  this  subject,  says:    "Suppose  the  bulb 


3I4  MECHANICAL   DENTISTRY. 

of  the  thermometer  gets  slightly  fractured,  and,  the  accident  not 
being  discovered,  the  vulcanizer  is  put  to  use,  what  then? 

"  If  the  damage  is  slight,  the  mercury  may  still  be  made  to  rise 
in  the  tube  at  high  temperatures,  but  will  not  truly  indicate  the 
full  heat  or  force  within.  Some  time  ago  I  had  some  difficulty 
in  producing  a  desirable  shade  in  my  vulcanite  work ;  it  was  too 
dark,  as  is  the  case  when  overheated,  and  I  came  to  the  conclu- 
sion that  the  gum  had  deteriorated  in  quality.  Other  samples  of 
gum  were  tried,  and  at  varying  lengths  of  time,  yet  with  the  same 
result. 

"  No  defect  could  be  discovered  in  the  thermometer  by  the  naked 
eye,  but  a  microscope  revealed  a  slight  crack  in  the  bulb,  and  the 
mystery  was  solved.  But  what  force  of  steam  was  produced  dur- 
ing these  almost  despondent  trials? 

"  Although  my  vulcanizer  would  safely  bear  a  pressure  of  100 
pounds  per  square  inch,  I  concluded  to  use  a  steam-gage  for  the 
future,  and  now  feel  a  security  in  its  use  positively  refreshing." 

The  unreliability  of  thermometers  in  connection  with  vulcanizers 
has  been  recognized  by  many  in  the  profession  who  have  testified 
to  their  uncertainty  and  insecurity  as  a  means  of  determining  with 
exactness  at  all  times  the  amount  of  steam  pressure  employed  in 
the  process  of  vulcanizing  at  a  high  heat. 

The  steam-gage  spoken  of  by  Dr.  Lawrence  seems  very  per- 
fectly to  fulfil  the  requirements  of  the  dentist,  and  may  justly 
claim  favorable  consideration  from  the  commendation  bestowed 
upon  it  by  the  distinguished  gentleman  who  has  brought  it  to 
the  notice  of  the  profession.  It  is  shown  in  Fig.  128.  The  follow- 
ing is  the  author's  own  account  of  the  instrument :  "  The  gage 
most  suitable  for  the  purpose  in  question  somewhat  resembles  a 
small,  circular  clock,  is  about  six  inches  in  diameter,  and  marked  to 
register  140  or  180  pounds  pressure,  with  pound  dots  near  the  outer 
circle  of  the  dial.     A  pointer  indicates  the  force  which  moves  it. 

"  This  size  is  better  than  a  smaller  one,  because  the  spring  inside, 
not  being  crowded  to  its  utmost  capacity  in  vulcanizing,  will,  of 
course,  retain  its  working  integrity  longer;  in  fact,  as  long  as  any 
dentist  now  living  will  be  personally  interested  in  the  matter.  They 
can  be  used  with  all  vulcanizers  generating  steam,  connecting  by 
means  of  three  or  four  feet,  or  as  much  more  as  may  be  convenient, 
of  small  pipe  having  a  U-shaped  bend,  or  a  single  coil  near  and 


RUBBER  OR  VULCANITE  BASE.  315 

under  the  gage  to  receive  the  condensed  steam,  as  water  alone  should 
enter  this  instrument. 

"  The  following  table  exhibits  a  range  of  pressure  sufficient  for 
vulcanizing  purposes,  with  the  temperature  necessary  to  produce  the 
same : 


Pressure 
in  lbs. 

Tempera- 
ture. 

Pressure 
in  lbs. 

Tempe  ra  ■ 
ture. 

Pressure 
in  lbs. 

Tempera- 
ture. 

Pressure 

in  lbs. 

Tempera- 
ture. 

60 

295° 

69 

3°S° 

78 

314° 

95 

328° 

61 

2960 

70 

3060 

79 

314° 

100 

332° 

62 

2980 

71 

307° 

80 

315° 

105 

335° 

63 

2990 

72 

308° 

81 

3160 

no 

339° 

64 

3000 

73 

3°9° 

82 

317° 

115 

342° 

65 

301° 

74 

3100 

83 

318° 

120 

345° 

66 

3020 

75 

3i  i.° 

84 

319° 

125 

349° 

67 

303° 

76 

312° 

85 

320° 

130 

352° 

68 

304° 

77 

313° 

90 

3240 

"  It  will  readily  be  seen  by  the  above  that  a  pressure  of  60  pounds 
requires  a  temperature  of  295  °  by  Fahrenheit's  scale  to  produce  it, 
and  85  pounds  3200,  at  which  latter  pressure  I  vulcanize,  running 
•one  hour,  and  with  the  most  satisfactory  results." 

Removing  the  Flask  after  Vulcanizing. — When  the  process 
-of  vulcanizing  has  been  conducted  a  sufficient  length  of  time,  the 
flame  is  turned  off  and  the  steam  discharged  through  the  safety- 
valve,  if  the  vulcanizer  is  provided  with  one;  or  the  lower  half  of 
the  boiler  may  be  placed  in  cold  water  until  the  contents  are  cooled 
down  to  about  2000.  When  time  will  permit,  however,  it  is  better 
to  let  the  vulcanizer  cool  gradually.  The  top  is  then  taken  off  and 
the  flasks  removed.  The  latter  should  always  be  allowed  to  cool 
gradually,  as  the  immersion  of  the  flask,  while  hot,  in  cold  water 
will  endanger  the  porcelain  teeth  by  a  too  sudden  change  of  tem- 
perature. Neither  should  the  flask  be  opened  while  hot,  for  the 
plate,  being  pliable  when  heated,  would  be  liable  to  suffer  some 
change  of  form  in  forcing  the  sections  of  the  flask  apart,  or  in 
removing  the  piece  after  separation  of  the  flask.  When  the  plate 
is  removed  from  the  flask,  detach  carefully  all  adhering  plaster  with 
a  pointed  knife,  and  cleanse  well  by  washing  with  a  stiff  brush. 

The  Finishing  Process. — The  rougher  and  more  redundant  por- 
tions of  the  rubber  are  first  removed  with  coarse  files  or  rasps,  fol- 
lowing with  those  of  a  finer  cut  (Fig.  132)  or  lathe  burs  (Fig.  134), 
until    all    parts    of    the    piece    accessible    to    such    instruments    are 


316  MECHANICAL   DENTISTRY. 

reduced  to  nearly  the  thickness  required.     The  excess  of  material 
Fig.    132.  Fig.    133. 


on  the  lingual   side  of  the  plate  and  other  points  not  admitting  of 
the  use  of  the  file  is  removed  with  scrapers  of  various  forms,  some 


RUBBER  OR  VULCANITE  BASE.  317 

of  which  are  shown  in  Fig.  133.  After  nearly  the  desired  thickness 
is  thus  obtained,  and  the  surface  rendered  somewhat  smooth  and 
uniform,  a  still  further  reduction  is  obtained  with  the  use  of  sand- 
paper, using  first  the  coarser  and  finishing  with  the  finer  numbers. 
The  final  polish  is  then  given  to  the  surface,  first  with  the  use  of 
finely-pulverized  pumice-stone,  and  afterward  with  either  prepared 
chalk  or  whiting.  The  best  method  of  applying  the  pumice  is  with 
flat,  circular  pieces  of  cork  of  various  sizes,  which  may  be  readily 
formed  by  attaching  them  to  the  lathe  and  reducing  them  to  the 
proper  size  and  shape  with  a  file  while  revolving.  The  chalk  or 
whiting  may  be  applied  upon  a  cotton  or  ordinary  brush  wheel. 
In  the  use  of  the  polishing  materials,  the  latter  should  be  kept 
constantly  and  freely  saturated  with  cold  water  throughout  the 
operation. 

Partial  Dentures  Constructed  on  a  Base  of  Rubber. — The  fore- 
going description  of  the  method  of  forming  entire  dentures  on  a 
base  of  rubber,  together  with  a  knowledge  of  the  manner  of  con- 
structing parts  of  sets  of  teeth  mounted  on  metallic  plates,  will 
render  any  extended  description  of  the  former  process,  as  it  relates 
to  partial  pieces,  unnecessary.  A  base-plate  of  the  required  thick- 
ness and  dimensions  is  accurately  adapted  to  a  model  of  the  parts, 
the  narrower  portions  passing  into  the  spaces  between  the  teeth 
being  stiffened  by  doubling  the  plate  at  these  points  with  an  addi- 
tional strip  of  the  material  used.  The  central  portion  of  the  plate 
may  also  be  temporarily  supported,  and  its  form  preserved,  by  fill- 
ing in  the  concavity  with  a  layer  of  stiffened  wax.  A  rim  of  wax 
is  then  attached  in  the  usual  manner  to  those  portions  of  the  plate 
occupying  the  vacuities  on  the  ridge,  when  the  plate  is  placed  in 
the  mouth  and  an  impression  of  the  points  of  the  opposing  teeth 
secured;  it  is  then  removed,  reapplied  to  the  model,  and  the  heel 
of  the  latter  extended  posteriorly  to  form  an  articulating  surface 
for  the  remaining  portion  of  the  antagonizing  model — the  latter 
being  formed  in  the  ordinary  way.  The  teeth  are  then  fitted  to  the 
Vacuities  in  precisely  the  same  manner  as  when  metallic  plates  are 
used,  and  the  wax  trimmed  to  the  required  fullness.  The  plate, 
with  the  teeth  attached,  is  then  placed  in  the  mouth  and  any  neces- 
sary corrections  made  in  the  arrangement  of  the  teeth;  after  which 
it  is  removed  and  readjusted. 

In  constructing  partial  sets  of  vulcanite,  it  is  of  the  first  im- 


318  MECHANICAL    DENTISTRY. 

portance,  when  forming-  the  mold,  that  the  relation  of  the  porcelain 
teeth  to  the  model  of  the  mouth  should  be  accurately  maintained, 
the  reasons  for  which  are  fully  set  forth  when  treating-  of  the 
formation  of  the  mold  or  matrix  for  full  sets.  To  secure  this  result 
with  certainty  the  following  method  should  be  adopted.  Having 
adjusted  the  plate  and  teeth  upon  the  model,  with  the  wax  trimmed 
and  carved  to  the  required  fullness,  place  the  model  in  the  lower 
section  of  the  flask  and  fill  in  with  plaster,  extending  it  up  to  the 
points  of  the  teeth,  binding  them  to  the  model,  and  making  the 
line  of  separation  of  the  sections  of  the  flask  at  that  point.  The 
ends  of  the  plaster  teeth  should  be  cut  away  sufficiently  to  allow  of 
a  ready  separation  of  the  sections.  Plaster  is  then  poured  in  for 
the  upper  section  of  the  mold,  and,  when  hard,  the  flask  is  parted 
and  the  wax  removed  from  the  model  and  teeth,  the  latter  being 
retained  in  the  lower  instead  of  the  upper  section  as  in  full  cases. 
Metallic    Clasps   Attached   to   Rubber   Plates. — Although    at- 

Fig.   135.  Fig.  136. 


mospheric  pressure  or  adhesion  should  be  made  available  in  all 
practicable  cases  as  a  means  of  retaining  parts  of  sets  of  teeth  in 
the  mouth,  yet  cases  frequently  present  themselves  necessitating 
the  employment  of  clasps.  These  may  be  of  rubber,  but  those 
formed  of  gold,  or  gold  alloyed  with  platinum,  are  more  reliable 
and  better  adapted  to  those  cases  where  the  spaces  between  the 
teeth  are  contracted. 

In  constructing  a  clasp,  first  bend  the  clasp  to  fit  the  tooth  accu- 
rately; then  make  the  attachment  by  which  it  is  to  be  held  to  the 
rubber  (this  may  be  done  by  soldering  a  thin  plate  of  gold  or  pla- 
tina  to  the  clasp  in  such  a  position  that  it  will  be  inclosed  in  the 
rubber)  ;  then  perforate  the  plate  with  numerous  small  holes,  which 
should  be  countersunk  on  both  sides  (Fig.  135).  This  plate  enter- 
ing the  base,  the  rubber  filling  the  holes  forms  pins  which  rivet  the 
clasp  securely  to  the  rubber  plate. 

(  h  the  attachment  may  be  made  in  this  manner:    On  the  parts 


RUBBER  OR  VULCANITE  BASE.  319 

of  the  clasp  that  can  be  covered  with  rubber  drill  one,  two,  or  three 
holes,  as  the  space  may  admit;  insert  gold  or  platina  wire,  solder 
with  gold  solder,  then  cut  off  at  proper  length,  and  head  them 
(Fig.  136)  ;  these  act  in  retaining  the  clasp  in  the  same  manner  as 
the  double-headed  pins  in  securing  the  tooth  to  the  base,  and  offer 
the  advantage  over  the  perforated  plate  of  being  more  easily 
manipulated  and  less  liable  to  become  displaced  in  packing  the 
mold.  The  clasp  is  to  be  attached  to  the  model  plate,  and  will  re- 
main secured  in  the  mold  when  it  is  opened. 

Substitution  of  Plate  for  Rubber  Teeth. — An  ordinary  plate 
tooth,    such   as   is   commonly   used   in    connection   with    a   metallic 
plate-base,    can   be   readily   rendered    suitable    for   a    rubber   base. 
This  is  done  by  soldering  a  narrow  strip  of  gold  plate  to  the  ends 
of  the  platinum  pins,  forming  a  loop  or  staple,  and  which,  imbedded 
in  the  rubber,  renders  the  attachment  very  secure.     A  narrow  arm 
of  rubber  extending  to  a  single  tooth  may  be  materi- 
ally   strengthened   by   placing   a   metallic   backing   on         Fig.  137. 
the  tooth   and   permitting  the   gold   strip,   perforated 
with  holes  or  roughened  on  its  edges,  to  pass   some 
distance  into  the  rubber,  as  seen  in  Fig.   137.     This 
method  may  be  resorted  to  with  signal  advantage  in 
cases  of  very  close  bite;  that  is,  where,  on  closure  of 
the  jaws,  the  points  of  the  opposing  teeth  encroach 
unduly  upon  the  space  to  be  filled,  extending  nearly  to  the  gum, 
requiring  the  tooth  of  replacement  to  be  as  thinly  formed  through- 
out its  length  as  possible. 

Repairing. — If  a  tooth  or  block  has  been  broken,  or  any  change 
is  to  be  made  in  the  position  of  either,  the  teeth  or  fragments 
thereof  are  removed,  and  an  irregularly  shaped  groove  or  dove- 
tail formed  in  the  base  occupying  the  space  to  be  supplied;  into 
this  space  the  tooth  or  teeth  are  properly  arranged  and  supported 
with  wax ;  the  dovetail  is  then  filled  in  with  wax,  giving  some 
additional  fullness  to  compensate  for  waste  in  finishing.  All  por- 
tions of  the  piece  except  the  lingual  face  of  the  plate  and  teeth  are 
then  imbedded  in  plaster  in  the  lower  section  of  the  flask.  The 
upper  section  of  the  mold  is  obtained  in  the  usual  way.  When 
separated  and  all  traces  of  wax  removed,  the  gum  is  packed  into 
the  cavity  around  the  tooth  or  teeth.  Grooves  are  then  cut  ex- 
tending  out   from   the   mold,   the   two   sections   heated   and   forced 


320 


MECHANICAL   DENTISTRY. 


together,  and  the  process  of  vulcanizing  conducted  in  the  usual 
manner,  the  same  time  and  degrees  of  heat  being  required  as  in  the 
first  instance.  The  renewed  heat  employed  renders  the  surface  of 
the  material  previously  vulcanized  somewhat  darker,  to  remove 
which  it  is  recommended  to  moisten  the  surface  with  dilute  nitric 
acid  for  a  short  time,  after  which  the  piece  is  thoroughly  washed, 
and  then  placed  for  a  few  minutes  in  an  alkaline  solution  to  remove 
any  remaining  traces  of  acid.  It  is  also  recommended  to  immerse 
the  case  in  alcohol  for  five  or  six  hours,  and  then  expose  it  to  the 
rays  of  the  sun  for  a  like  period  of  time. 

Dr.  A.  A.  Blount,  of  Geneva,  Switzerland,  in  the  Ohio  State 
Journal,  suggests  the  following  method  of  replacing  a  broken 
crown  without  removing  the  entire  section :  "  Finding  it  impossible 
to  match  the  injured  block,"  he  says,  "  I  ground  the  broken  tooth 
down  to  the  gum,  as  one  would  for  a  pivot  tooth,  and,  as  I  had  often 
done  before  in  mending  a  continuous-gum  piece,  selecting  a  plain 
rubber  tooth  the  exact  size  and  shape,  ground  it  carefully  and 
accurately  to  fit,  cementing  it  in  place  with  a  plastic  cement,  which 
served  to  hold  it  firm  and  prevent  the  rubber  from  coming  through 
to  the  front.  The  plate  being  prepared  as  usual  for  mending,  the 
piece  was  vulcanized.  After  being  finished,  no  one  could  tell  that 
the  block  had  ever  been  fractured.  This  method  of  repairing 
broken  blocks,  mounted  upon  Watt's  metal,  will  be  found  very  prac- 
tical, as  it  is  somewhat  difficult  to  replace  a  broken  block  upon  that 
base." 

One  of  the  most  frequent  repairs  we  are  called  upon  to  make  is 
a  fracture  through  the  center  of  an  upper  partial  denture,  the 
break  extending  from  the  region  of  the  central  incisors  backward. 
The  method  of  repair  in  such  cases  is  quite  simple,  consisting  in 
first  accurately  adjusting  the  two  parts  of  the  plate  and  fastening 
them  in  their  correct  relation  to  each  other  with  adhesive  wax  or 
shellac.  This  should  be  dropped  over  the  entire  length  of  the 
crack  by  an  assistant,  while  the  sections  of  the  plate  are  being 
held  in  correct  apposition.  Plaster  is  then  mixed  and  poured  into 
the  plate,  forming  a  cast  of  the  palatine  surface  of  the  mouth. 
After  this  hardens  sufficiently,  the  wax  or  shellac  is  removed, 
which  permits  the  sections  of  the  plate  to  be  taken  up  separately. 
The  line  of  the  fracture  is  now  cut  out  or  enlarged  upon  either 
side  with  a  large  bur  revolved  by  the  dental  engine,  or  it  may  be 


RUBBER  OR  VULCANITE  BASE. 


321 


accomplished  with  a  file  or  saw.  Dovetails  are  then  cut  on  either 
side  with  a  jeweler's  saw,  and  the  sections  replaced  upon  the  cast. 
The  work  at  this  stage  is  shown  in  Fig.  138. 

The  opening  between  the  two  halves  and  the  dovetailed  spaces 
are  then  covered  with  wax,  the  case  invested  in  a  flask  in  the 
usual  way,  the  flask  reopened,  and  wax  removed.  The  space 
between  the  two  halves,  with  the  dovetailed  spaces,  are  then  care- 
fully packed  with  rubber,  when  it  is  vulcanized  and  finished  in  the 
usual  way. 

The  whole  subject  of  repairing  rubber  plates  is  so  fully  and 
clearly  described  by  Dr.  George  B.  Snow,  in  an  article  entitled, 
"  Repairing  Vulcanite  Plates,"  that  his  processes  are  here  given  in 

Fig.  138. 


detail.  The  writer  would  premise  that  he  has  long  since  abandoned 
the  older  method  of  "  under  cutting "  in  repairing  rubber  plates, 
and  would  emphasize  what  is  stated  by  Dr.  Snow,  "  that  perfect 
union  can  be  obtained  in  such  cases  if  the  surfaces  of  contact  are 
freshly  cut,  absolutely  clean,  and  properly  roughened. 

"  It  is  not  unusual  to  see  vulcanite  plates  which  have  been  cracked 
or  broken,  and  repaired  by  what  may  be  termed  the  '  hole  and 
plaster '  system.  Holes  are  drilled  through  the  plate  along  the 
edges  of  the  crack,  and  a  new  thickness  of  rubber  superimposed 
upon  a  mass  which,  possibly,  is  already  too  thick  for  comfort  or 
convenience,  the  old  crack  still  remaining  as  a  weak  point  to  occa- 
sion further  breakage.     No  advantage  was  taken  of  any  possibility 


322 


MECHANICAL   DENTISTRY. 


of  union  between  the  old  and  new  material,  the  dentist  having  been 
obviously  ignorant  of  the  fact  that  perfect  union  can  be  obtained  in 
such  cases  if  the  surfaces  of  contact  are  freshly  cut,  absolutely  clean, 
and  properly  roughened. 

"  The  great  point  to  be  remembered  in  repairing  or  making  any 
addition  to  a  vulcanite  plate  is  that  the  new  and  old  material  will 
unite  perfectly,  and  with  such  firm  adhesion  that  the  plate  will  be 
practically  as  good  as  new,  if  the  surfaces  of  the  old  plate  where 
union  with  the  new  material  is  desired  are  freshly  filed,  absolutely 
clean,  properly  roughened,  and  of  sufficient  area.  To  insure  these 
results,  wax  should  not  be  melted  upon  the  surfaces  of  union  in 
waxing  up,  and  removal  of  the  wax  from  the  mold  should  be  accom- 
plished by  means  of  instruments,  and  not  by  hot  water,  unless, 
possibly,  for  the  removal  of  very  small  particles  which  cannot  other- 
wise be  gotten  rid  of.  Any  amount  of  the  old  material  desired  may 
be  cut  away,  and  its  place  supplied  by  new ;  and  thus  any  change 
wished  may  be  effected.  In  case  of  breakage  or  cracking,  the  plate 
should  be  cut  away  so  that  the  old  defects  will  be  wholly  obliter- 
ated and  new  material  supplied. 

"  As  a  first  instance,  suppose  a  partial  lower  plate,  supplying  the 
loss  of  the  bicuspids  and  molars  on  both  sides  of  the  mouth,  to  be 
broken  through  the  bar  which  extends  from  one  side  of  the  mouth 
to  the  other  behind  the  incisors.  The  fracture  is  generally  a  clean 
one,  resembling  that  of  glass  or  porcelain,  and  the  two  pieces  may 
be  brought  into  apposition  with  certainty.  The  dentist  holding  the 
parts  together  in  exactly  the  right  position,  the  assistant  covers  the 
lingual  side  of  the  plate  at  the  point  of  fracture  with  a  few  drops  of 
hot  shellac  from  a  shellac  stick.  A  little  cold  water  follows,  and 
the  two  parts  of  the  plate  are  firmly  cemented  together.  A  brace 
is  now  extended  across  from  the  molars  on  one  side  to  those  on  the 
other,  by  laying  a  burnt  match  on  the  grinding  surfaces  of  the 
respective  teeth,  and  fastening  both  ends  with  a  few  drops  of  hot 
wax.  By  this  means  sufficient  strength  is  obtained  to  allow  of  the 
plate  being  safely  handled.  A  piece  of  paper  or  sheet-wax  is  cut 
to  fit  and  reach  across  the  lingual  space  at  the  lower  edge  of  the 
plate,  and  fastened  therein  with  wax,  a  coat  of  shellac  varnish 
is  applied  to  the  paper,  the  surface  lathered  with  soap-suds,  and 
rinsed,  and  a  model  run  in  the  same  manner  as  in  filling  an  impres- 
sion. 


RUBBER  OR  VULCANITE  BASE.  323 

"  After  this  has  hardened,  the  plate  is  removed  from  the  model, 
which  is  then  given  a  coating  of  liquid  silex.  This  is  always  pref- 
erably done  in  repairing  plates,  at  the  time  when  the  plate  is  first 
removed  from  the  model.  The  rubber  bar  may  now  be  cut  away, 
on  either  side  of  the  fracture,  by  a  jeweler's  saw,  the  cut  being  made 
diagonally,  so  as  to  make  what  is  termed  a  '  scarf '  joint.  The  sur- 
faces should  be  further  roughened  by  making  a  series  of  shallow 
parallel  cuts  across  them  with  the  saw,  a  thick  separating  file,  or  a 
thin  wheel-bur.  The  parts  of  the  plate  are  then  placed  upon  the 
model,  waxed  up,  and  flasked,  the  model  and  buccal  surfaces  of  the 
teeth  being  covered  with  plaster,  and  the  parting  made  so  that  the 
plate  will  be  retained  upon  the  model,  while  the  pieces  of  the  bar 
can  be  readily  removed.  After  the  flask  is  opened,  the  pieces  are 
removed,  the  usual  gateways  cut,  and  the  packing,  vulcanizing,  and 
finishing  done  as  usual. 

"  In  the  case  of  an  entire  lower  set  broken  through  the  center,  it 
will  be  seen  that  the  same  directions  will  apply,  excepting  as  to  the 
amount  of  rubber  to  be  cut  away.  A  free  cut  should  be  made  on 
the  lingual  side,  extending  through  under  the  teeth,  to  and  includ- 
ing the  labial  band;  so  that  the  broken  surfaces  will  be  entirely 
obliterated,  and  at  least  x/%  of  an  inch  in  width  of  new  rubber  sup- 
plied between  the  cut  surfaces.  An  engine-bur  will  do  much  of 
this  work  nicely,  and  a  wheel-bur  is  very  convenient  for  the  purpose 
of  scoring  the  surface.  Making  the  model,  flasking,  and  packing 
will  be  done  as  before. 

"  If  one  of  the  incisor  blocks  be  broken,  and  needs  replacement, 
a  new  one  can  be  fitted  after  the  model  is  obtained,  and  the  remain- 
ing steps  of  the  process  followed  as  has  been  described. 

"  Upper  plates  are  sometimes  cracked  in  the  center,  the  crack 
extending  from  under  and  between  the  incisor  teeth  backward  over 
the  palate.  This  often  happens  from  the  amount  of  rubber  just 
behind  the  incisors  being  insufficient.  It  is  not  unusual  to  see  it 
cut  away  at  this  point,  so  that  the  pins  are  almost  or  quite  ex- 
posed, the  plate  having  its  usual  thickness  at  a  very  short  distance 
behind  the  teeth.  A  much  larger  amount  of  material  will  be  toler- 
ated here  than  is  usually  employed,  and  often  with  benefit,  not 
only  to  the  strength  of  the  plate  but  to  the  articulation  of  the  wearer. 
The  curve  of  the  surface  of  the  plate  should  be  made  to  re- 
semble that  of  the  palate  before  the  removal  of  the  teeth,  and  it 


324 


MECHANICAL   DENTISTRY. 


will  be  found  that  the  extra  thickness  may  extend  for  y2  of  an 
inch  behind  the  teeth  without  annoyance  to  the. patient. 

"  A  proper  curvature  to  the  surface  of  the  plate,  just  behind  the 
incisors,  will  do  much  to  prevent  the  disagreeable  whistling  in  mak- 
ing the  s  sound,  and  will  assist  in  giving  the  correct  enunciation  to 
sh,  zh,  and  other  Unguals. 

"  If  the  cracked  plate  fits  a  flat  mouth,  a  model  can  often  be 
drawn  from  it  as  it  is;  but  if  the  arch  is  high,  and  the  gums  pro- 
jecting, it  is  better,  after  thoroughly  cleansing  and  drying  the 
plate,  to  finish  the  cracking  by  breaking  the  plate  entirely  in  two. 
The  two  halves  may  now  be  fastened  together  by  dropping  shellac 
upon  the  lingual  side,  and  a  model  secured,  from  which  either 
half  of  the  plate  can  be  easily  removed.  The  whole  palatal  por- 
tion of  the  plate  can  then  be  removed  by  a  saw  cut,  leaving  only 
a  narrow  margin  on  the  lingual  surface  inside  the  teeth.  The 
remainder  of  the  surfaces  of  fracture  are  cut  away  as  directed  in 
case  of  the  lower  plate,  the  new  surfaces  roughened,  the  pieces  of 
the  old  plate  replaced  upon  the  model  (which  has  received  its 
coating  of  liquid  silex),  waxed  up,  flasked,  packed,  and  vulcanized, 
the  teeth  being  retained  upon  the  model  as  before  described. 
The  plate,  when  finished,  will  show  the  old  rim  and  a  margin  of 
the  old  rubber  inside  the  teeth. 

"  It  is  sometimes  desirable  to  change  the  substance  of  the  plate 
entirely,  as  in  case  of  supposed  mercurial  poisoning  by  red  rubber; 
or  at  least  to  put  what  red  rubber  there  may  be  about  the  plate 
entirely  out  of  sight,  and  to  reduce  its  quantity  to  a  minimum. 
If  this  is  to  be  done  to  the  plate  last  under  consideration,  it  should 
be  prepared  for  flasking  as  described,  excepting  that  the  labial 
band  should  be  cut  away,  and  everything  arranged  so  that  the 
plate  can  be  separated  from  the  model  when  flasked.  The  parts 
cut  away  should,  of  course,  be  replaced  by  wax.  The  cast  is  now 
set  in  the  flask  so  as  to  leave  the  parting  at  the  upper  edges  of  the 
gums.  The  plaster  is  varnished  and  oiled,  and  more  plaster  built 
on  against  the  labial  sides  of  the  teeth,  extending  from  their  cut- 
ting edges  to  the  edge  of  the  flask,  and  again  varnished  and  oiled, 
so  that  the  appearance  will  now  be  precisely  similar  to  a  plate 
flasked  so  as  to  be  retained  upon  the  model.  The  ring  of  the 
flask  is  now  put  in  place  and  filled,  and  the  plaster  allowed  to 
harden. 


RUBBER  OR  VULCANITE  BASE.  325 

"  When  the  flask  is  separated,  the  teeth  will  be  found  in  its  ring 
section.  A  few  blows  of  the  hammer  will  dislodge  them,  with  the 
piece  of  plaster  built  against  their  labial  surfaces.  This  is  care- 
fully broken  away,  in  two  pieces,  if  possible,  which  are  preserved, 
and  the  teeth  and  rubber  incasing  them  are  left.  The  rubber  is 
now  filed  away  as  much  as  is  practicable,  leaving  none  of  the  old 
rubber  in  sight,  and  removing  enough  from  the  palatal  surface  to 
make  a  new  fit  to  the  model.  The  teeth  and  plaster  are  replaced 
in  the  flask,  and  the  case  is  ready  for  packing  and  vulcanizing; 
when  finished,  none  of  the  old  rubber  will  be  seen,  and  the  plate 
will  be  practically  as  good  as  though  the  teeth  had  been  removed 
from  the  old  plate  and  reset. 

"  It  is  evident  that  the  change  from  red  to  black  rubber  just 
described,  can  be  made  with  a  whole  plate  or  a  broken  one  indif- 
ferently. If  a  change  of  articulation  and  a  new  fit  to  the  mouth 
is  also  desired,  on  account  of  shrinkage  of  the  gums,  the  plate 
should  be  prepared  so  as  to  draw  from  the  model,  and  a  few  small 
pieces  of  wax  put  in  the  palatal  side  to  bear  upon  the  alveolar 
ridge,  and  give  the  right  articulation  by  trial  in  the  mouth,  the 
center  of  the  plate  being  cut  away  to  facilitate  the  fitting  of  the 
plate  to  the  model.  A  fresh  model  of  the  mouth  being  secured 
from  an  impression,  the  plate  is  waxed  on  to  it,  the  case  is  flasked 
with  a  false  piece  of  plaster  built  against  the  labial  sides  of  the 
teeth,  as  has  been  described,  and  the  plate  removed  and  cut  away 
as  much  as  desired,  a  considerable  amount  being  always  taken 
from  its  palatal  surface." 

Beaded  or  Grooved  Dentures. — For  the  exclusion  of  air  and 
moisture  from  between  the  artificial  denture  and  the  mucous 
membrane  of  the  mouth,  a  groove  may  be  cut  in  the  plaster  cast,  as 
shown  in  Fig.  139,  which  is  taken  from  an  article  in  the  Dental 
Cosmos,  contributed  by  Dr.  W.  Storer  How.  The  bead  must  be 
carried  continuously  around  the  outer  portion  of  the  cast,  just 
inside  the  plate  line.  This  inclosure  will  produce  a  chamber-like 
function  of  the  entire  inner  surface  of  the  denture,  see  Fig.  140. 
The  resulting  greatly  increased  adhesion,  especially  noticeable  in 
mouths  having  flat  and  soft  surfaces,  is  a  gratifying  effect  of  the 
device. 

Partial  dentures,  as  shown  in  Fig.  141,  may  thus  be  securely  re- 
tained, and  the  simplicity  of  the  process  is  hardly  less  remarkable 


\z6 


MECHANICAL   DENTISTRY. 


than   the   successful    result.     It   is   only   essential   that   the    scraper 
shall  be  shaped  and  operated  to  produce  a   suitably   smooth,  nar- 

FlG.   139. 


row,  half-round  groove  in  the  model,  and  follow  previously  studied 
lines  along  the  palatal  soft  parts  and  at  the  merging  of  the  muscles 
in   the   gums.     The   inclosures   may   be    of   any    size   or    shape    or 

Fig.   140. 


Fig.  141. 


number  that  a  careful  preobservation  of  the  character  and  confor- 
mation of  the  mouth  may  indicate. 


CHAPTER  XXIV. 

CELLULOID  BASE. 

The  employment  of  celluloid  in  prosthetic  dentistry,  notwith- 
standing the  very  general  failure  which  attended  its  first  intro- 
duction into  practice,  came  rapidly  into  general  professional  favor 
as  a  cheap,  convenient,  and  serviceable  base  for  artificial  dentures. 
With  the  more  recent  improvements  in  the  manufacture  and  sea- 
soning of  blanks,  more  perfectly  adapted  appliances  for  molding, 
and  a  more  extended  acquaintance  with  the  peculiar  and  distinctive 
characteristics  of  this  material,  it  has,  in  the  practice  of  many, 
superseded,  in  a  great  measure,  other  plastic  vegetable  substances 
for  the  purpose  indicated. 

It  is  more  in  harmony  with  the  soft  tissues  of  the  mouth,  more 
cohesive  in  texture,  approximates  more  nearly  the  natural  gum 
color,  contains  less  vermilion  pigment  in  its  composition  than 
does  rubber,  and  is  less  objectionable  by  reason  of  the  comparative 
cleanliness  accompanying  its  manipulation. 

Celluloid,  as  at  present  produced,  and  when  properly  manipu- 
lated, does  not,  in  any  appreciable  degree,  undergo  change  of  form 
after  molding  by  warping  either  in  or  out  of  the  mouth,  as  was 
formerly  the  case.  It  loses  somewhat  the  freshness  and  clearness 
of  its  original  pink  color,  however,  after  having  been  in  use  for 
some  time,  in  many  cases  in  a  very  marked  degree. 

Though  not  bearing  so  perfect  a  resemblance  to  the  complexion 
of  the  healthy  gum  tissue  as  the  porcelain  imitations,  yet  the  near 
approximation  of  celluloid  to  the  desired  color  makes  the  use  of 
single  plain  teeth  admissible  for  permanent  dentures,  and  this  is 
unquestionably  its  crowning  merit,  and  makes  it  the  most  desirable 
of  all  the  so-called  "  cheap  bases."  The  indiscriminate  and  almost 
universal  employment  of  block  or  sectional  gum  teeth  in  con- 
nection with  rubber  has  done  more  to  degrade  the  prosthetic 
department  of  dental  practice  than  all  other  causes  combined. 
The    optional  arrangement  of    each    individual    tooth    to    meet    the 

327 


328 


MECHANICAL   DENTISTRY. 


requirements  of  special  cases  in  respect  to  expression,  articulation, 
and  antagonism  is  one  of  the  absolute  and  indispensable  require- 
ments of  a  perfect  artificial  denture. 

Composition  and  Manufacture. — The  following  is  the  sub- 
stance of  Dr.  C.  J.  Essig's  account  of  the  composition  and  manu- 
facture of  celluloid: 

Celluloid  is  derived  from  cellulose,  a  woody  fiber,  constituting 
the  framework  or  foundation  of  plants. 

Linen,  cotton-wool,  hemp,  etc.,  are  examples  of  cellulose.  For 
the  manufacture  of  celluloid,  the  cellulose  is  first  converted  into 
paper;  hemp  is  the  form  of  cellulose  employed  for  this  purpose, 
because  it  has  been  found  to  make  the  strongest  paper,  and  the 
stronger  the  paper  the  better  the  celluloid. 

The  hemp  is  first  converted  into  paper  in  the  usual  way  by 
paper  machines.  By  this  process  the  form  of  the  material  under- 
goes a  physical  change  only,  while  chemically  it  remains  the  same, 
viz.,  nearly  pure  cellulose,  and  has  a  formula  of  C6H10O5.  The 
cellulose,  now  in  the  form  of  hemp-paper,  is  converted  into  pyrox- 
ylin by  a  process  technically  known  as  "  conversion,"  this  change 
being  effected  by  immersing  the  hemp-paper  in  a  strong  mixture 
of  nitric  and  sulphuric  acids  for  a  sufficient  length  of  time,  when  it 
is  removed  from  the  acids  and  washed  thoroughly. 

It  is  now  still  in  the  form  of  paper,  but  it  will  be  found  to  have 
increased  in  weight  about  70  per  cent.,  and  to  have  become  highly 
explosive,  taking  fire  at  about  300 °  F. 

Pyroxylin,  then,  is  the  chief  ingredient  in  celluloid,  and  is 
reduced  to  a  pulp  in  a  machine  similar  to  that  used  in  paper- 
making;  a  thorough  mixture  is  then  made  of: 

Pyroxylin,    ioo  parts. 

Camphor,    4° 

Oxid  of  zinc,    2 

Vermilion,    0.6 

Some  alcohol  is  used  to  soften  the  camphor.  The  mass  is  now 
put  under  a  hydraulic  pressure  of  2000  pounds  to  the  square  inch. 
The  cylinders  in  which  it  is  pressed  have  a  small  orifice  in  the  side 
near  the  bottom,  and  when  pressure  is  made  the  celluloid  is  forced 
out  through  this  orifice. 

The  immense  pressure  is  to  condense  or  solidify  the  celluloid, 


CELLULOID    BASE. 


329 


and  as  it  is  forced  out  it  is  cut  off  in  pieces  of  the  proper  size,  and 
molded  by  pressure  and  heat  to  the  forms  in  which  we  receive  it. 
At  this  point  the  blanks  are  still  soft,  and  require  to  be  seasoned; 
this  requires  about  two  months,  during  which  time  they  are  kept 
in  a  room  at  a  temperature  of  1600  F. 

Processes  Preliminary  to  Molding. — While  many  of  the  proc- 
esses entering  into  the  construction  of  artificial  dentures,  with  cel- 
luloid as  a  base,  are  essentially  the  same  as  those  required  when 
rubber  is  used,  yet  there  are,  in  many  important  respects,  modifica- 
tions of  practice  made  necessary  by  the  peculiar  nature  and  behavior 
of  the  material  employed. 

When  the  distinctive  characteristics  of  celluloid  are  well  under- 
stood, and  the  operator  is  familiar  with  the  approved  methods  of 
working  it,  no  unusual  difficulties  attend  its  successful  manipula- 
tion. To  attain  uniformity  and  satisfactory  results,  however,  it  is 
absolutely  necessary  that  there  should  be  a  faithful  compliance 
with  every  manipulative  detail,  however  seemingly  unimportant, 
which  experience  in  the  use  of  this  substance  has  demonstrated  to 
be  essential. 

Plaster  Model. — The  inferior  plasticity  of  celluloid,  compared 
with  vulcanizable  rubber,  when  exposed  to  the  action  of  heat,  and 
the  consequent  greater  pressure  necessary  to  mold  it  into  any 
given  form,  makes  it  necessary  to  give  to  the  plaster  model  the 
greatest  practicable  hardness  and  strength.  To  secure  these  im- 
portant qualities  it  is  recommended  to  use  the  best  quality  of 
coarse  builder's  plaster,  which,  though  it  does  not  set  so  quickly 
as  the  finer  and  whiter  varieties,  becomes  much  harder  and  more 
resistant  to  pressure  when  thoroughly  dried.  Increased  hardness 
will  be  secured  by  adding  to  the  plaster  mixture  a  small  quantity 
of  clean  white  river  or  lake  sand  or  marble  dust. 

A  smoother  face  will  be  given  to  the  model  by  .first  coating  the 
surface  of  the  impression  with  a  moderately  thin  mixture  of  fine 
plaster,  and,  as  this  begins  to  set,  fill  in  with  the  coarser  variety  for 
the  body  of  the  model. 

The  plaster  for  the  model  should  be  mixed  as  thick  as  can  be 
well  poured,  taking  care,  as  it  is  slowly  introduced,  to  expel  any 
confined  air  by  tapping  or  shaking  the  impression-tray  as  the  plas- 
ter flows  in. 

In  cases  where  there  is  any  considerable  anterior  projection  of 


33° 


MECHANICAL   DENTISTRY. 


the  alveolar  ridge  in  front,  above  or  below,  the  corresponding 
portion  of  the  plaster  model  is  liable  to  be  crushed  under  the 
pressure  necessary  to  mold  celluloid.  To  prevent  such  accident, 
it  has  been  recommended,  in  addition  to  the  expedient  to  be 
mentioned  hereafter,  to  place  in  the  front  part  of  the  impression 
a  curved  piece  of  brass  plate  punched  full  of  holes,  }/2  or  Y\  of  an 
inch  wide,  which,  when  the  impression  is  filled,  will  be  imbedded  in 
the  central  portion  of  the  plaster  ridge,  and  extend  some  distance 
into  the  body  of  the  model. 

Metal  Casts. — In  extreme  cases,  where  the  ridge  is  very  thin 
and  the  projection  spoken  of  excessive,  it  is  safer  and  better 
practice  to  substitute  metal  for  plaster  in  forming  the  model.  In 
this  case  the  latter  may  be  obtained  by  pouring  block-tin  or 
Babbitt  metal  directly  into  the  plaster  impression,  which  should 
first  be  thoroughly  dried,  and  the  cavity  for  the  air-chamber  formed 
before  pouring. 

A  solid  metal  cast,  however,  should  never  be  employed  when 
there  is  any  considerable  undercutting,  as  is  often  the  case  on 
either  side  of  the  median  line  in  front,  forming  the  canine  fossa, 
and  posteriorly  underneath  the  maxillary  tuberosities,  since,  in 
such  cases,  it  will  be  impossible  to  detach  the  metal  cast  from  the 
case  when  molded.  The  separation  can  be  readily  effected  by 
substituting  a  metal  shell  for  the  solid  cast.  The  shell  is  formed 
in  the  following  manner :  Secure  a  perfect  mold  of  the  plaster 
model  in  sand,  and  pour  into  this  fused  block-tin  of  the  purest 
kind,  pouring  it  as  hot  as  can  be  without  producing  bubbling 
of  the  metal.  As  the  metal  cools  first  at  the  surface,  a  shell  will 
form  externally  in  a  few  seconds,  when  the  box  containing  the 
mold  should  be  inverted  and  the  central  fluid  mass  poured  out 
quickly  at  the  back  part  of  the  mold  in  order  to  secure  the 
thinnest  portion,  of  the  shell  in  front,  where  it  should  not  be 
thicker  than  ordinary  card  paper.  A  little  practice,  with  a  few 
failures  at  first,  will  enable  the  operator  to  secure  the  desired  thick- 
ness of  the  shell  with  tolerable  exactness.  When  obtained,  the 
shell  is  filled  in  with  hard-setting  plaster  to  form  the  metal-faced 
model  to  be  used  in  molding  the  celluloid.  When  the  case  is 
finished  and  the  plaster  removed  from  the  shell,  the  overlapping 
borders  of  the  latter  may  be  readily  drawn  in  toward  the  center 
with    pliers,   and   the   shell    disengaged    from   the   undercut   spaces. 


CELLULOID    BASE. 


331 


To  facilitate  its  removal,  the  shell,  before 
filling  in  with  plaster,  may  be  divided 
vertically  at  intervals  with  a  fine  saw, 
extending  the  cuts  from  the  margins  to 
near  the  summit  of  the  ridge. 

Waxing  or   Modeling. — After  hav- 
ing arranged  the  teeth   for  any  given 
case,  place  them  with  the  trial  plate  on 
the   model,    and   build   out   with   wax, 
paraffin    and    wax,    or    modeling    com- 
pound.    In  carving  or  modeling  these 
materials,  much  time  and  labor  may  be 
saved  in  final  finishing  of  the  piece,  and 
a  more  compact   surface  given  to  the 
celluloid,  by  securing  in  the  first  place 
the  exact  form  and  fullness  required  in 
the  completed  set.     When  this  is  done 
with  instruments  especially  adapted  to 
the  purpose,  the  general  forms  of  which 
are  represented  in  Fig.  142,  additional 
smoothness  of  the  surface  may  be  ob- 
tained with  a  blowpipe  flame 'applied  in 
such  a  way  as  to  produce  simple  surface 
fusion  of  the  wax  or  other  material. 
The  palatal  and  exterior  surfaces  may 
then  be  covered  with  No.  60  tin-foil, 
carefully  burnished  into   close  contact. 
A  closer  imitation  of  the  granular  ap- 
pearance of  the  natural  gum  exteriorly 
may  be  obtained  by  pitting  or   "  stip- 
pling "  the  surface  with  a  small  pointed 
instrument,  care  being  taken  not  to  per- 
forate, but  simply  indent,  the  foil ;  or  a 
flat-faced  serrated  plugger  may  be  used 
for  the  same  purpose. 

Investing. — The  piece  prepared  as 
above  is  then  placed  in  a  flask  especi- 
ally designed  for  celluloid  (see  Fig. 
143),  invested  in  plaster,  and 'the  mold 


Fig.  142. 


/ 


332 


MECHANICAL   DENTISTRY, 


or  matrix  formed  in  the  same  manner  as  practised  when  rubber  is 
used.  In  case  the  ridge  overhangs,  or  is  undercut,  the  model, 
before  being  incased  in  the  lower  section  of  the  flask,  should  be 
cut  across  diagonally,  with  the  slope  toward  the  heel  of  the  model, 
thus  depressing  the  latter  posteriorly.  By  this  means  the  projecting 
portion  of  the  ridge  will  be  brought  more  directly  in  a  line  with  the 
pressure  in  closing  the  flask. 

It  is  quite  as  important  that  the  incasing  plaster  forming  the 
matrix  should  be  as  hard  and  resistant  to  pressure  as  that  entering 
into  the  composition  of  the  plaster  model.  If  this  condition  is  not 
secured,  there  will  be  great  danger,  not  only  of  fracture  of  the 

Fig.  143. 


model  for  the  want  of  adequate  lateral  support,  but  of  displacement 
of  the  teeth  by  being  forced  into  the  plaster.  So  important  is  the 
right  condition  and  manipulation  of  plaster  in  the  use  of  celluloid, 
that  the  writer  feels  warranted  in  adding,  to  what  has  already  been 
said  in  this  connection,  the  following  judicious  comments  contained 
in  a  pamphlet  issued  by  the  manufacturers  of  celluloid: 

"  Plaster  should  always  be  mixed  as  thick  as  possible,  and,  if  con- 
venient, allowed  to  set  over  night,  with  the  flask  open,  and  dried  in 
a  warm  place,  as  it  is  thereby  rendered  much  harder.  Simple  as  the 
operation  is,  comparatively  few  understand  how  to  mix  plaster  so 
as  to  get  the  greatest  strength  and  resistance  to  pressure.     The 


CELLULOID   BASE. 


333 


proper  way  to  mix  plaster  for  both  models  and  filling  flask  is  as 
follows :  First,  stir  the  plaster  as  thick  as  can  be  well  poured,  taking 
care  that  there  is  no  excess  of  water;  pour  some  of  this  into  the 
flask  or  impression  to  be  filled,  and  shake  down  well.  Then,  into 
what  remains  in  the  bowl,  stir  more  plaster  until  you  have  a  mass 
so  thick  that  it  can  be  piled  up.  With  this  the  flask  is  filled  up  and 
thoroughly  shaken  down.  It  is  surprising  how  much  plaster  can 
be  stirred  in  after  the  first  is  poured  out,  and  also  how  thick  a  mass, 
such  as  described,  will  settle  down  in  the  flask  without  bubbles. 
The  thinner  plaster  first  poured  in  will  run  and  be  driven,  by  the 
thicker  afterward  added,  into  all  the  crevices,  and  most  of  it  will 
escape  from  the  flask,  leaving  a  body  of  solid,  resisting  plaster  that 
cannot  be  obtained  by  the  ordinary  method  of  mixing." 

In  flasking  the  case,  the  line  of  separation  between  the  upper  and 
lower  sections  should  be  along  the  borders  of  the  plate.  This  is  par- 
ticularly necessary  when  the  gum  is  "  stippled."  When  the  piece 
is  incased,  and  the  plaster  has  sufficiently  hardened,  the  two  sec- 
tions of  the  flask  should  be  carefully  separated,  and  this  can  be 
done  with  greater  safety  to  the  model  and  other  portions  of  the 
matrix,  and  with  less  liability  of  loosening  and  detaching  the  teeth 
from  the  plaster,  by  first  applying  just  sufficient  heat  to  the  flask  to 
soften  the  wax  and  trial  plate,  being  careful  not  to  melt  the  wax  by 
too  great  or  long-continued  heat. 

When  the  flask  is  separated,  all  portions  of  wax  or  other  material 
should  be  carefully  and  thoroughly  removed  from  the  mold,  and  if 
any  remain,  not  accessible  to  instruments,  the  section  or  sections 
of  the  flask  containing  remains  of  wax  should  be  placed  in  a  clean 
vessel  under  clean  water  and  well  boiled  until  all  is  expelled.  The 
thin,  frail  edges  encircling  the  matrix  in  both  sections  of  the  flask 
should  then  be  cut  away  somewhat,  and  well  rounded  to  prevent 
fracture  and  consequent  mixing  of  particles  of  plaster  with  the  cel- 
luloid in  molding.  When  this  is  done,  put  the  flask  together  and 
see  if  there  is  ample  room  for  the  "  nose  "  of  the  model  to  pass  the 
edge  of  the  matrix. 

To  permit  the  escape  of  surplus  material  in  molding,  either  of 
the  following  plans  may  be  adopted :  I .  Cut  two  concentric  grooves 
in  the  plaster  of  the  upper  or  lower  section  completely  encircling 
the  matrix,  the  inner  one  not  less  than  %.  or  j4  of  an  inch  from  the 
margin  of  the  mold,  and  the  other  at  the  border  of  the  flask,  the 


334 


MECHANICAL   DENTISTRY. 


inner  side  of  the  latter  forming  a  part  of  the  outer  groove.  2. 
Bevel  the  plaster  around  the  mold,  commencing  at  the  margins  of 
the  tin-foil  C,  and  extending  it  to  the  sides  of  the  flask,  as  shown  at 
B,  Fig.  144. 

In  no  case  should  cross  grooves  be  made  communicating  with  the 
matrix,  as  these  afford  too  ready  an  exit  for  surplus  material,  and 
prevent  that  "  back  pressure  "  so  essential  to  a  complete  and  com- 
pact filling  of  the  mold.  The  grooves  should  be  deep  and  ample 
enough  to  receive  all  surplus,  otherwise  it  would  be  difficult,, 
if  not  impossible,  to  close  the  flask  perfectly.  In  the  use  of  gum 
teeth,  holes  may  be  drilled  in  the  matrix  inside  the  teeth,  opposite 

Fig.  144. 


each  joint,  not  over  ^  of  an  inch  in  diameter,  and  as  deep  as  it  may 
be  deemed  necessary.  These  act  as  waste'  gates,  and  relieve  the 
blocks  from  pressure. 

Selection  and  Preparation  of  the  Celluloid  Plate  or  Blank. — 
The  mold  having  been  prepared  in  the  manner  described,  a  suit- 
able blank  should  be  selected,  and,  as  it  is  important  that  this 
should  be,  as  nearly  as  possible,  the  size  and  general  form  of  the 
mold,  a  good  assortment  of  plates,  for  both  entire  and  partial 
pieces,  should  be  at  command  from  which  to  select  for  any  given 
case.  Special  attention  is  directed  to  this  important  requirement. 
Celluloid  does  not,  like  rubber,  flow  together  and  intimately  inter- 


CELLULOID   BASE.  335 

mix  when  exposed  to  heat  and  pressure.  If,  therefore,  the  blank  is, 
in  any  considerable  degree,  wider  than  the  model,  or  its  central  or 
palatal  portion  fuller  and  deeper  than  that  of  the  model,  the  material, 
when  under  pressure,  will  lap  or  fold  upon  itself  along  the  lateral 
walls  of  the  arch,  and,  failing  to  unite,  will  form  grooves  or  fissures. 
On  the  other  hand,  if  it  is  not  wide  or  deep  enough,  the  material  is 
liable  to  be  stretched  and  torn.  The  blank  should  be  just  large 
enough  to  fill  all  parts  of  the  mold  perfectly,  with  some  slight  ex- 
cess, and  the  central  portion  should  always  be  somewhat  thicker 
than  the  corresponding  part  of  the  trial  or  pattern  plate. 

As  celluloid  cannot  be  depended  on  to  flow  from  one  part  of  the 
mold  to  another,  it  is  important  that  there  should  not  only  be  an 
excess  of  material,  but  that  this  excess  should  be,  as  nearly  as 
practicable,  distributed  throughout  all  portions  of  the  matrix.  A 
neglect  of  this  precaution  will  result  either  in  an  imperfect  filling  of 
the  mold  in  some  places,  and  consequent  defect  of  the  plate,  or  a 
porous  condition  of  the  celluloid  will  be  found  wherever  the  mate- 
rial, though  apparently  filling  the  mold,  has  not  been  impacted  with 
sufficient  force. 

The  selected  blank  should  be  conformed  as  nearly  as  possible  to 
the  shape  of  the  mold  by  heating  it  in  boiling  water  and  pressing  it 
with  the  fingers  into  the  section  of  the  matrix  containing  the  teeth ; 
after  which  the  necessary  fullness  of  the  several  parts  of  the  blank 
may  be  obtained  by  dressing  away  redundant  portions  with  files,  a 
small  bracket-saw,  or  the  knife,  first  softening  the  plate  in  boiling 
water  before  using  the  latter. 

Greater  exactness  in  the  required  amount  of  celluloid  necessary 
in  any  given  case  may  be  obtained  by  measurement,  the  simplest 
method  being  by  the  use  of  the  Starr  instrument  for  measuring, 
illustrated  in  the  chapter  on  Vulcanite.  It  must  be  remembered, 
however,  that  this  device  only  determines  the  aggregate  amount  of 
material  necessary,  and  that,  while  it  may  be  a  safe  guide  in  the  use 
of  rubber,  which  flows  freely,  it  may  lead  to  failure  when  celluloid 
is  employed,  unless  care  is  taken  that  all  parts  of  the  blank  corre- 
spond with  the  capacity  of  the  mold. 

A  more  reliable  though  somewhat  tedious  method  of  securing 
exactness  in  the  quantity  and  distribution  of  material  necessary, 
and  which  acquires  special  value  in  cases  where  there  is  unusual 
danger  of  fracture  of  the  model  or  teeth,  and  especially  of  the  latter 


336  MECHANICAL   DENTISTRY. 

when  glim  teeth  are  used  and  these  are  ground  very  thin,  is  the 
following,  given  by  a  correspondent  of  the  Dental  Cosmos:  "  After 
preparing  the  case  ready  to  flask,  remove  the  teeth  from  the  pat- 
tern, stop  the  pin-holes,  then  remove  the  pattern  and  carefully  flask 
it.  When  the  mold  is  ready,  remove  all  the  wax  or  material  of  the 
pattern ;  place  the  celluloid  '  blank ' ;  apply  heat,  and  cast  the  same 
as  if  for  final  case.  Remove  the  flask  from  the  heater;  place  it  in 
the  clamp  and  cool  rapidly.  When  it  is  entirely  cool,  remove  it 
from  the  flask,  and  trim  as  carefully  as  for  final  case  until  the 
blank  is  almost  the  same  as  the  pattern  in  thickness  (it  always 
comes  out  thicker) .  Now  you  have  a  blank  with  but  little  excess ; 
— only  what  the  vacuum  and  pins  displace,  or  slightly  more,  and 
exactly  the  shape  of  the  pattern,  minus  the  teeth.  Set  up  the 
case  again,  being  careful  to  make  the  pattern  the  same  size;  flask, 
and  when  ready  remove  the  pattern;  if  doubtful  as  to  amount  of 
excess,  pare  the  edges  of  the  mold  slightly,  which  will  be  all 
that  is  needed.  Replace  the  blank;  apply  heat,  when  but  moderate 
pressure  will  be  found  necessary  to  bring  the  flask  entirely  to- 
gether. If  dry  heat  is  preferred,  dip  the  edges  of  the  blank  to 
come  in  contact  with  the  pins  in  spirit  of  camphor  for  a  few  min- 
utes before  casting." 

Before  the  blank  is  placed  in  the  flask  preparatory  to  molding, 
some  provision  should  be  made  against  adhesion  of  the  plaster  to 
the  plate.  This  may  be  done  by  oiling  the  surface  of  the  model, 
or  by  coating  it  and  other  portions  of  the  matrix  with  either  collo- 
dion or  liquid  silex,  or  by  rubbing  the  surfaces  well  with  French 
chalk  or  powdered  soapstone;  or  a  layer  of  tin-foil  may  be  inter- 
posed between  the  model  and  blank.  The  following  novel  method 
of  coating  the  surface  of  the  model  with  tin  is  recommended  by 
Charles  P.  Alker,  of  Bordeaux,  France :  "  Reduce  ordinary  col- 
lodion with  about  three  times  its  bulk  of  ether,  and  add  pow- 
dered tin  until  the  solution  is  well  impregnated  with  the  metal. 
The  tin  is  the  same  that  is  sometimes  used  for  coating  plaster 
images.  When  properly  mixed  and  applied  with  a  brush,  an  even 
covering  of-  tin  is  formed  upon  the  model,  so  dense  as  to  closely 
resemble  tin-foil,  and  so  firm  as  to  not  be  detached  by  boiling 
water  or  heat.  The  plate  is  readily  cleansed  with  a  coarse  brush, 
and  presents  the  appearance  of  having  been  made  in  a  metallic 
mold." 


CELLULOID    BASE. 


337 


More  perfect  results,  however,  it  is  believed,  can  be  obtained  in 
the  use  of  a  metal-faced  model  in  connection  with  the  use  of  tin-foil, 
as  before  described.  A  piece  thus  incased  in  metal  will  require  no 
more  final  finishing"  than  is  necessary  to  remove  surplus  material 
and  dress  and  polish  edges. 

The  case,  thus  described,  is  now  ready  for  molding. 

Molding. — The  various  machines  or  heaters  now  generally 
employed  in  molding  celluloid  into  dental  plates  contemplate  the 
use  of  either  glycerin  or  oil,  steam  or  dry  heat,  for  the  purpose 
of  producing  the  requisite  plasticity  of  the  material  subjected  to 
pressure.  There  is  considerable  diversity  in  the  form  and  con- 
struction of  heaters  designed  to  utilize  the  several  mediums  for 
the  conduction  of  heat,  as  well  as  differences  in  the  modes  of 
applying  pressure,  and  while  each  has,  doubtless,  some  special 
points  of  merit  not  possessed  by  others,  satisfactory  results  may, 
with  careful  and  intelligent  manipulation,  be  attained  by  the  use  of 
any  one  of  the  many  recommended.  The  limits  of  this  work  will 
only  permit  the  introduction  of  such  as  are  believed  to  be  in  most 
general  use. 

Hot  Moist  Air  (so-called  "  Dry-Heat ")  Machines. — In  the  use 
of  these  heaters,  the  water  with  which  the  plaster  is  impreg- 
nated is  relied  upon  to  produce  the  steam  necessary  to  carry  off 
all  excess  of  camphor  from  the  celluloid  in  the  process  of  molding. 
An  essential  point  by  this  method  is  to  have  the  plaster  in  the 
flask  thoroughly  wet,  and  this  may  be  better  attained  by  setting 
the  flask  in  a  vessel  of  water  before  placing  it  in  the  heater.  To 
provide  against  insufficiency  of  moisture  in  the  plaster,  a  small 
quantity  of  water  may  be  introduced  into  the  tank  before  applying 
heat. 

Fig.  145  represents  a  modeling  or  packing  machine  of  the  class 
here  spoken  of,  and  is  designated  as  the  "  Best."  The  inside 
chamber  is  of  cast-iron,  surrounded  by  a  sheet-iron  casing.  The 
lid,  of  cast-iron,  forming  a  part  of  the  clamp,  is  pierced  for  the 
passage  of  three  wrought-iron  screw-bolts — the  nuts  being  on 
the  upper  side  and  easy  of  access.  When  these  nuts  are  turned 
for  the  purpose  of  closing  the  clamp,  the  bottom  portion  of  the 
clamp  is  drawn  up  by  each  revolution  away  from  the  flame,  thus 
avoiding  the  danger  of  overheating  the  plate,  and  securing  a 
uniform  heat.     The  bottom  of  the  cast-iron  chamber  and  the  lid 


338  MECHANICAL   DENTISTRY. 

are  pierced  with  holes,  to  allow  a  circulation  through  the  chamber, 
for  the  purpose  of  carrying  off  the  camphor  which  is  disengaged 
in  the  process. 

With  the  celluloid  blank  adjusted  to  its  proper  position  in  the 
flask,  the  latter  is  placed  in  the  clamp  and  the  top  screwed  down 
until  it  slightly  presses  the  clamp.  It  is  then  placed  in  the  oven  or 
tank  and  heat  applied. 

If  gas  is  used,  the  form  of  burner  shown  underneath  the  heater  in 
Fig.  145,  which  gives  a  pure  blue  flame  without  smoke,  may  be  used. 
If  gas  cannot  be  commanded,  however,  any  of  the  alcohol  or  kero- 
sene lamps  commonly  employed  in  vulcanizing  may  be  substituted; 
or  the  "  Hot  Blast  Oil  Stove,"  especially  adapted  to  the  "  Best " 
machine,  and  exhibited  in  connection  with  the  latter  in  Fig.  146. 

Having  applied  the  heat,  it  is  of  the  first  importance  that  un- 
remitting attention  should  be  given  to  the  process  of  molding  until 
it  is  completed.  If  pressure  is  applied  before  the  celluloid  is  ren- 
dered somewhat  plastic,  or  too  great  force  is  exerted  during  the 
earlier  stages  of  the  process,  and  without  sufficient  intervals  of 
rest,  there  is  danger  of  crushing  or  fracturing  the  model  and  of 
impairing  the  articulation  by  displacement  of  the  teeth.  On  the 
other  hand,  the  nature  of  celluloid  is  such  that  if  it  is  exposed  to 
a  temperature  of  2700,  without  being  under  pressure,  the  camphor 
evaporates,  and  the  material,  besides  being  rendered  hard  and  in- 
tractable, is  puffed  up,  exactly  as  a  loaf  of  bread  is  raised  by  yeast, 
and  filled  with  air-cells,  and  thus  rendered  porous. 

Celluloid  begins  to  soften  at  about  225 °,  and  will  then  yield 
slightly  to  pressure,  but  this  should  be  applied  very  gently  at  first, 
with  no  more  force  than  can  be  readily  exerted  with  the  thumb 
and  finger.  As  the  heat  increases,  and  the  celluloid  becomes 
more  and  more  plastic  and  yielding,  the  pressure  should  be  corre- 
spondingly increased,  but  always  interruptedly,  giving  the  material 
time,  between  each  turn  of  the  screw  or  nuts,  to  escape  from  under 
the  pressure.  No  considerable  amount  of  pressure  will  be  re- 
quired in  any  case  until  near  the  close  of  the  operation,  when  the 
mold  is  completely  impacted,  and  the  excess  is  being  forced  into 
the  grooves  or  gateways  as  the  flask  comes  together. 

At  this  point  considerable  force  will  be  necessary  to  close  the 
flask  perfectly,  and  somewhat  longer  intervals  of  time  should  occur 
between  each  turn  of  the  screw  or  nuts. 


CELLULOID    BASE. 
Fig.   145. 


339 


Fig.    146. 


340 


MECHANICAL    DENTISTRY, 


During  the  progress  of  the  molding,  the  flask  should  be  with- 
drawn occasionally  for  inspection.  If,  in  the  case  of  central 
pressure,  the  flask  is  found  to  be  closing  unevenly,  it  should  be 
loosened  in  the  clamp  and  readjusted  in  such  manner  as  to  correct 
the  faulty  approximation.  No  difficulty  will  be  experienced  in 
this  respect  in  the  use  of  clamps  provided  with  screw-bolts,  as 
pressure  may  be  applied  at  any  point,  and  the  flask  be  made  to 
close  uniformly  without  the  necessity  of  shifting  the  latter. 

The  moment  the  flask  is  completely  closed  the  heat  should  be 
turned  off,  and  the  piece  allowed  to  cool  gradually.  In  no  in- 
stance should  the  flask  be  removed  from  the  clamp  until  it  is 
stone  cold.  In  cases  where  the  material  is  of  extra  thickness,  or 
where  the  shape  of  the  blank  is  totally  altered,  longer  season- 
ing is  advisable,  and  the  flask  should  be  placed  near  a  stove  or 
over  a  register  (keeping  it  closed  by  a  clamp,  or  by  an  instru- 
ment or  piece  of  iron  put  through  the  holes  in  the  standard)  for 
half  a  day  or  more,  at  a  temperature  not  over  1400.  If  these 
directions  are  observed,  no  trouble  from  warping  plates  will  be 
experienced. 

Molding  in  Steam. — In  using  the  steam  machine,  care  should 
be  taken  to  keep  it  in  good  order.  The  screw  should  be  well  oiled 
with  only  the  best  sperm  oil,  which  will  not  gum,  and  kept  so  that  it 
can  be  easily  turned  with  the  thumb  and  finger.  If  the  machine, 
when  received  from  the  depot,  works  hard,  the  screw  should  be  run 
out,  the  gland  unscrewed,  and  the  rubber  packing  loosened  up,  so 
that  it  will  not  bind  the  screw.  Do  not  turn  it  down  tight  again 
until  you  heat  it  up,  when,  if  it  begins  to  leak,  it  can  easily  be  tight- 
ened. Bear  in  mind  that  turning  this  gland  merely,  prevents  the 
escape  of  steam,  and  does  not  affect  the  pressure  on  the  flask. 

The  safety-valve  should  be  kept  free  from  gum,  and  if  either  it 
or  the  screw  is  clogged,  it  should  be  well  cleansed  with  kerosene. 
This  valve,  in  the  machine  now  sold,  is  so  constructed  that  it 
blows  off  at  about  275 °,  a  temperature  that  celluloid  will  bear  very 
well ;  and  as  the  heat,  so  long  as  water  remains  in  the  boiler,  cannot, 
if  the  safety-valve  is  kept  in  order,  be  raised  above  that  point,  it  is 
impossible  to  barn  a  plate  in  this  machine.  While  this  is  true,  it 
is  also  true  that  too  long  an  exposure  to  even  275  °  in  steam 
tends  to  injure  the  quality  of  the  celluloid,  and  for  this  reason  the 
heat  should  be  continued  no  longer  than  necessary,  but  should  be 


CELLULOID    BASE.  34 1 

reduced  at-  once  by  blowing  off  steam  as  soon  as  the  molding  is 
completed.  The  first  machines  were  constructed  with  the  safety- 
valve  much  heavier,  and  all  in  one  piece,  and  were  adjusted  to  a 
temperature  of  nearly  3000,  which  was  higher  than  necessary  or 
advisable.  It  is  recommended,  therefore,  that  those  having  that 
style  of  valve  should  cut  off  about  one-fourth  in  weight  from  the 
lead  weight,  which  can  easily  be  done  by  removing  a  little  wire 
which  passes  through  the  stem  and  weight.  A  modern  valve  will 
be  furnished  when  ordered.  When  molding,  fill  the  boiler  partly- 
full  of  water.  The  amount  is  not  material,  but  there  should  always 
be  enough  to  cover  the  ribs  at  the  bottom.  Have  the  screw  well 
turned  back,  until  the  plunger,  when  placed  in  position,  will  rest 
against  the  top  of  the  boiler,  otherwise  the  flask  may  be  pressed 
upon  while  screwing  down  the  cover  and  the  cast  injured.  Turn 
down  the  cover  snugly ;  see  that  the  gland  is  turned  back,  and  the 
screw  works  freely.  Many  failures  have  occurred  by  neglecting 
this  simple  matter.  If  it  works  hard,  it  is  impossible  to  tell  how 
much  or  how  little  pressure  is  being  exerted ;  there  may  be  too 
much,  and  blocks  or  cast  be  broken ;  or  too  little,  and  the  plate 
made  porous.  In  all  methods  of  working  celluloid,  the  sense  of 
feeling  is  the  best  guide  as  to  when  and  how  hard  to  turn;  but  in 
order  to  have  this,  there  must  be  perfect  freedom  of  motion  of  the 
parts.  The  time  elapsing  before  turning  is  not  reliable,  as  it  varies 
with  the  heat  employed,  the  temperature  at  starting,  the  amount  of 
water  in  the  boiler,  the  drafts  of  air  to  which  the  flame  may  be 
subjected,  etc. 

After  placing  the  flasks  in  position,  turn  down  the  screw  very 
gently,  with  thumb  and  finger,  until  you  feel  it  touch  the  flask. 
Fill  the  cup  with  alcohol  and  light  it,  or  light  the  gas.  The  safety- 
valve  is  made  in  two  parts.  The  upper  portion  may  be  suspended 
by  the  pins  in  the  lead  weight ;  the  valve  will  now  blow  off  steam 
(if  in  proper  order)  at  a  temperature  of  225 °.  Until  this  occurs,  no 
particular  attention  is  necessary,  but  from  that  time  the  exclusive 
attention  of  the  operator  should  be  given  to  the  molding.  Many 
failures  occur  from  the  want  of  this,  for  the  plate  may  be  easily 
injured  from  too  much  heat  without  proper  pressure.  But  fifteen 
or  twenty  minutes,  at  the  most,  will  be  required  from  this  point, 
with  proper  heat,  and  nothing  else  should  be  attended  to. 

At  the  point  when  the  steam  escapes   from  the  valve  with  the 


3-P  MECHANICAL    DENTISTRY. 

upper  portion  suspended,  the  plate  will  soften,  and  the  screw  will 
be  felt  to  yield  to  light  pressure  with  thumb  and  finger.  The  upper 
weight  should  now  be  dropped  down.  Turn  the  screw  very  care- 
fully, stopping  when  you  feel  the  resistance  increase;  as  soon  as  it 
yields  again,  turn  it  more,  going  slowly  and  carefully  at  first,  but 
increasing  the  pressure  somewhat  as  the  steam  gets  up,  which  you 
will  know  by  occasionally  raising  the  valve.  It  is  just  here  that 
judgment  is  required  to  avoid,  on  the  one  hand,  too  much  pressure 
before  the  material  is  sufficiently  softened,  which  would  result  in 
fracture  of  the  cast  or  blocks,  disarranging  the  articulation,  or  a 
"  flaky  "  plate ;  and,  on  the  other,  too  little  pressure  after  the  heat 
is  up,  which  would  result  in  injuring  the  quality  of  the  material. 
The  pressure  should  be  followed  up  as  the  heat  rises  and  the  screw 
yields,  the  object  being  to  get  the  whole  of  the  plate  under  pressure, 
in  every  part  of  the  mold,  by  the  time  the  steam  blows  off  quite 
sharply  and  steadily  on  raising  the  safety-valve.  After  this  the 
pressure  should  be  increased,  but  time  should  always  be  given 
between  the  turns  for  the  slowly  flowing  celluloid  to  escape  from 
under  the  pressure.  Toward  the  close  of  the  process,  the  pressure 
should  be  considerable ;  in  fact,  about  all  that  can  be  applied  with 
the  machine,  and  should  be  continued  as  long  as  the  screw  can  be 
turned.  If  the  operation  has  been  properly  timed,  the  s,team  will 
blow  off  at  the  safety-valve  at  about  the  time  the  molding  is  com- 
pleted and  the  alcohol  in  the  cup  is  consumed.  If  it  should  blow 
off  before  that,  no  harm  would  be  done,  as  the  heat  cannot  become 
too  great  if  the  safety-valve  is  kept  in  proper  condition.  These 
remarks  apply  to  the  use  of  alcohol  in  the  cup  furnished  with  the 
machine.  If  any  other  heat  is  used,  the  flame  should  be  sufficient 
to  complete  the  process  within  thirty  to  forty  minutes.  If  more 
than  this  time  is  consumed  in  the  molding,  the  quality  of  the  plate 
is  injured. 

Do  not  allow  the  water  to  be  all  converted  into  steam,  as  the 
steam  would  then  become  superheated,  and  a  dangerous  condition 
ensue  or  the  plate  be  ruined,  while  the  safety-valve  would  not  indi- 
cate it.  Always  have  plenty  of  water  in  the  boiler,  and  if  steam 
should  cease  to  issue  on  raising  the  valve,  the  heat  should  be  at 
once  withdrawn. 

It  lias  been  demonstrated  by  experimental  tests,  and  is  now  very 
generally  conceded,  that  the  best  results  are  obtained  in  the  use  of 


CELLULOID   BASE. 


343 


celluloid  by  subjecting  it  to  dry  heat  in  the  process  of  molding, 
the  material,  when  exposed  to  a  high  temperature  under  such  a 
condition,  retaining  most  perfectly  its  form,  color,  and  consistency. 
Hence  the  celluloid  presses  of  more  recent  introduction,  while 
they  are  also  equally  well  adapted  to  vulcanizing  by  the  same 
means,  are  provided  with  a  distinct  chamber  in  which  hot  air,  of  a 
higher  temperature  than  can  be  safely  employed  with  glycerin  or 
steam,  is  utilized  to  secure  the  greatest  practicable  plasticity  of  the 


Fig.  147. 


Open. 


Closed. 


celluloid.     Approved  appliances  of  this  kind  are  those  devised  by 
Drs.  Seabury  and  Evans. 

Molding  by  Dry  Heat. — When  the  investment  is  thoroughly 
dried,  insert  and  carefully  adjust  the  selected  blank;  place  the 
flask  in  the  oven  (see  Fig.  147)  immediately  under  the  screws;  see 
that  the  two  sections  are  so  placed  that  the  guide-pins  will  enter 
properly  into  the  lugs ;  turn  down  the  screws  until  they  bear  lightly 
upon  the  top  of  the  flask,   and  close  the  machine.     In   less   than 


344  MECHANICAL   DENTISTRY. 

five  minutes  the  material  will  be  sufficiently  softened  to  permit  the 
commencement  of  the  molding.  The  screws  will  turn  readily 
with  the  thumb  and  finger  (using  the  smaller  key-wrench),  when 
the  blank  is  properly  softened.  Close  the  flask  gradually,  stopping 
occasionally  if  the  resistance  is  very  material.  Usually,  if  the 
temperature  is  about  3000,  the  flask  can  be  closed  in  ten  minutes; 
but  if  a  very  thick  blank  is  used,  the  molding  must  proceed 
slowly.  As  soon  as  the  flask  is  closed — unless  a  lock  flask  is  used 
— the  flame  should  be  extinguished,  the  door  opened,  and  the 
machine  allowed  to  cool.  If  a  lock  flask  is  used,  it  may  be  re- 
moved and  thoroughly  cooled  before  opening  it,  the  oven  being 
meanwhile  ready  for  another  case.  The  cooling  may  be  accom- 
plished rapidly,  if  necessary,  by  placing  the  flask  in  water.  When 
perfectly  cold,  remove  the  plate  from  the  investment ;  it  will  be 
found  enveloped  in  the  tin-foil  which  had  been  burnished  to  the 
wax  plate.  Peel  off  the  foil.  The  celluloid  will  present  a  hard, 
brightly-polished  surface,  received  from  its  contact  with  the  foil, 
and  will  need  no  further  finishing  than  cutting  off  the  excess  of 
material  and  smoothing  down  the  edges. 

In  the  use  of  material,  as  a  base  for  dentures,  possessing  prop- 
erties so  extremely  sensitive  to  heat  as  that  of  celluloid,  and  so 
liable  to  suffer  changes  of  color  and  structure  materially  affecting 
its  usefulness  by  a  misapplication  of  heat  and  faulty  manipulation, 
everything  that  contributes  to  a  better  understanding  of  its  be- 
havior in  the  process  of  molding  must  be  of  interest  and  practical 
value.  The  following  experiments  of  Dr.  J.  Stewart  Spence,  of 
San  Francisco,  Cal.,  throw  some  additional  light  upon  the  subject. 
He  says : 

"  Having  just  made  more  than  30  experiments  with  celluloid 
and  the  New  Mode  Heater,  I  have  met  with  some  interesting  facts, 
of  which,  during  two  years'  previous  use  of  the  apparatus,  I  was 
ignorant.  The  main  results  I  will  now  give  before  relating  the 
experiments,  thus  inverting  the  usual  order  of  placing  results  last, 
for  the  sake  of  perspicuity. 

"  1.  Plaster  investments  require  one  and  a  half  hours  to  dry  in 
the  oven  of  the  heater,  with  the  thermometer  at  4000,  and  half  an 
hour  more  to  raise  their  heat  to  3200.  Drying  them  over  a  gas- 
burner  takes  nearly  as  long,  and  loosens  the  plaster  from  the  flask. 
A   thermometer   placed    between    the    slightly    separated    halves    of 


CELLULOID    BASE.  345 

the  flask  in  the  oven  indicates  when  this  heat  is  reached,  at  which 
time  a  blank  previously  prepared,  should  be  expeditiously  in- 
serted. 

"  2.  Celluloid  may  be  molded  in  from  five  to  ten  minutes  at  3200  ; 
in  about  twenty  to  twenty-five  minutes  it  degenerates,  becoming 
brown,  hard,  brittle,  and  porous,  and  in  twenty-five  to  thirty  min- 
utes it  burns  up. 

"  3.  Celluloid  will  burn  at  either  high  or  low  temperatures,  ac- 
cording to  the  length  of  time  it  is  exposed  to  them,  as  well  as 
their  degree  of  heat.  Thus  it  is  unsafe  to  leave  it  at  even  a  low 
heat  for  a  long  time,  as  in  slow  cooling. 

"  4.  Celluloid  is  more  liable  to  spoil  if  not  under  pressure,  and 
those  parts  of  the  blank  least  subject  to  pressure  are  most  liable  to 
come  out  damaged.  Therefore  flasks  should  be  closed  with  all 
expedition. 

"  5.  Celluloid,  unless  worked  at  a  high  temperature,  so  as  to  flow 
readily,  and  with  well-hardened  plaster,  will  press  the  model  out  of 
shape  and  teeth  out  of  position. 

"  6.  Steam  brought  in  contact  with  heated  celluloid  makes  it  puff 
up  and  degenerate. 

"  7.  Plaster  retains  heat  longer  than  metal,  and  therefore  plates 
left  in  the  oven  to  cool  may  spoil  or  burn  up  even  when  the  tem- 
perature of  the  heater  has  fallen  to  a  low  degree. 

"  8.  Tin-foil  discolors  celluloid  at  a  high  heat,  making  it 
browner. 

"  9.  Celluloid  after  molding  is  hardest  at  the  surface,  as  may  be 
clearly  seen  in  a  plate  that  has  been  slightly  overheated,  it  being 
porous  internally,  but  very  hard  on  its  surface. 

"  Instead  of  giving  a  copy  of  my  record  of  these  experiments, 
which  would  be  unnecessarily  prolix,  I  will  give  a  condensed  ac- 
count of  them  by  series. 

"  1st  Series.  To  test  the  heat  of  the  oven.  I  placed  in  the  dry 
oven  a  separate  thermometer,  which,  with  the  door  closed,  regis- 
tered the  same  as  that  outside ;  then  reversed  them  with  similar 
results.  Removing  the  central  screw  from  the  top  did  not  reduce 
the  temperature  perceptibly.  Removing  the  door  reduced  it  a  few 
degrees.  Removing  both  door  and  screw  caused  a  rapid  decrease 
from  320 °  to  290°. 

"  2d  Series.  To  test  the  heat  of  oven  with  plaster  in  it.     I  filled  a 


346  MECHANICAL    DENTISTRY. 

half  flask  with  plaster  and  placed  it  in  the  oven  with  a  ther- 
mometer on  the  floor  beside  it,  of  course  closing  the  door,  the 
outer  thermometer  standing"  at  3200.  After  twenty  minutes  the 
inner  thermometer  had  reached  only  3000,  showing  the  cooling 
effects  of  the  plaster  on  the  air  of  the  oven.  Moved  the  ther- 
mometer on  to  the  plaster ;  the  thermometer  fell  considerably, 
and  while  the  outer  thermometer  rose  in  thirty  minutes  to  4400, 
the  inner  reached  only  2900  ;  steam  was  then  admitted  to  the  oven, 
and  it  ran  instantly  up  to  340 ° ;  steam  was  then  shut  off,  and  the 
outer  thermometer  maintained  at  about  3600  for  thirty  minutes 
longer,  by  which  time  the  inner  reached  3200.  At  this  point 
some  steam  was  let  off,  which  ran  the  outer  thermometer  200  be- 
low the  inner,  showing  that  plaster  is  slow  to  part  with  its  heat  as 
well  as  to  receive  it. 

"  Further  experiments  were  made  in  drying  plaster,  both  in  the 
oven,  with  steam  and  without  it,  and  out  of  the  oven  over  a  gas- 
burner  ;  also  with  plaster  mixed  with  pulverized  pumice  and  mixed 
with  marble-dust.  It  was  found  that  in  the  oven  with  either  steam 
or  dry  heat,  and  the  outer  thermometer  at  4000,  about  thirty  min- 
utes were  required  to  dry  and  heat  a  small  half  flask  of  plaster  to 
3200,  and  about  two  hours  for  a  full  flask.  Done  over  a  gas- 
burner,  under  an  inverted  flower-pot,  a  little  less  time  was  con- 
sumed, but  the  investments  loosened  from  the  flasks ;  under  higher 
heats  they  become  burnt  and  badly  checked.  Those  mixed  with 
pumice  and  marble-dust  took  nearly  as  long  to  heat  and  became 
softer  than  the  plaster  alone,  and  so  were  thereafter  abandoned. 

"  3d  Series.  Testing  celluloid  in  the  oven  without  the  presence  of 
plaster,  steam,  or  pressure.  A  piece  of  celluloid  placed  in  the  oven 
at  3200,  the  heat  rising,  burned,  after  slight  swelling,  at  3600.  A 
second  piece  remained  in  thirty  minutes  with  the  heat  at  3200, 
swelled  slightly,  and  crumbled  to  powder  on  being  taken  out.  A 
third  piece  left  in  three  minutes  at  3200  was  taken  out  a  little 
swollen  and  somewhat  brittle  and  porous. 

"  4th  Series.  Testing  celluloid  in  the  oven  with  plaster  and  with 
moisture.  A  half  flask  of  moist  plaster  was  placed  in  the  oven, 
and  on  it  a  piece  of  celluloid  and  a  thermometer.  The  outer  ther- 
mometer, starting  from  3200,  rose  to  4400,  and  then  fell  to  3600  in 
about  sixty  minutes,  by  which  time  the  inner  thermometer  reached 
3200,    and    the    celluloid,    after    great    swelling,    ignited.      (In    the 


CELLULOID    BASE.  347 

previous  series  of  experiments  the  celluloid  had  swollen  but  about 
one-tenth  as  much  as  it  did  in  these.)  Next  a  half  flask  of 
previously  dried  plaster  was  inserted,  and  the  inner  thermometer 
raised  to  3400,  when  a  piece  of  celluloid  was  dropped  in,  and 
burned  in  five  minutes.  A  second  piece  at  about  3300  puffed  up 
in  ten  minutes,  and  would  probably  have  exploded  in  five  more  if 
I  had  not  varied  the  experiment  by  admitting  steam  to  test  its 
effects,  which  were  a  greatly  increased  swelling  and  then  gradual 
shriveling  to  a  thin  wafer.  (That  steam  does  not  produce  ignition 
was  also  demonstrated  elsewhere,  when  its  admission  ran  the  inner 
thermometer  up  to  3400,  and  yet  afterward,  when  the  steam  was 
shut  off,  the  celluloid  burned  at  3200.)  In  the  next  test  the  dry  half 
flask  was  again  used,  but  the  outer  thermometer  was  lowered  to  3200, 
which  ran  the  inner  one  down  much  lower,  but  in  forty  minutes 
they  tallied,  during  which  forty  minutes  the  celluloid  after  the  first 
fifteen  minutes  began  to  puff,  and  in  ten  minutes  more  had  reached 
full  size,  and  then  for  fifteen  minutes  slowly  shrank,  then  exploded. 

"  Both  thermometers  being  now  at  3200,  a  piece  of  blank  was 
left  in  fifteen  minutes,  and  on  being  taken  out  crumbled  to  powder 
under  the  slightest  pressure.  A  second  blank,  in  twenty-five 
minutes,  at  300 °,  came  out  not  crumbling  so  badly.  A  third  at 
2800,  for  thirty  minutes,  was  slightly  swelled  and  somewhat  brittle 
and  porous. 

"  5th  Series.  Testing  celluloid  in  the  oven  with  pressure  and  plas- 
ter. A  full  flask  of  plaster  was  placed  in  the  oven,  and  its  tempera- 
ture raised  to  that  of  the  outer  thermometer,  3200  ;  then  a  piece  of 
celluloid  was  placed  in  the  flask,  which  was  closed  down  in  three 
minutes,  and  in  five  more  the  piece  was  removed  from  the  flask  in 
perfect  condition.  A  second  piece  was  then  inserted,  closed  in 
ten  minutes,  and  removed  from  the  oven,  and  in  five  minutes  more 
opened  in  perfect  condition.  A  third  piece  was  left  in  twenty 
minutes,  and  in  five  more  opened  in  perfect  condition,  not  even 
discolored.  A  fourth  piece  was  given  twenty-five  minutes  in  the 
oven  and  ten  more  before  opening  the  flask,  with  disastrous  results ; 
it  had  crumbled  to  a  brown  powder. 

"  This  fifth  series  of  tests  show  that  the  material  in  question 
remains  perfect  under  pressure  longer  than  without  it.  But  it  is  to 
be  remembered  that  the  investment  here  used  must  have  lost  some 
of  its  heat  while  out  of  the  oven.     Later  trials  seem  to   indicate 


348  MECHANICAL   DENTISTRY. 

twenty  minutes  as  the  longest  time  that  celluloid  can  safely  be  left  at 
3200.  As  a  side  issue,  the  cohesion  of  the  material  was  tested 
during  this  series ;  freshly-filed  surfaces  were  placed  together,  and 
apparently  joined,  but  they  separated  under  a  strong  strain. 

"6th  Series.  Testing  the  effect  of  steam  on  the  celluloid  at  3200. 
The  same  investment  was  used  as  in  Series  5,  and  the  flask  closed 
in  ten  minutes,  when  steam  was  admitted.  In  ten  minutes  more 
the  blank  came  out  spoiled,  being  disintegrated,  whitish,  and  sticky- 
I  have  seen  celluloid  take  on  this  soft  and  white  condition  when 
heated  in  water  above  2700. 

"7th  Series.  Testing  the  flowing  qualities  of  celluloid  at  3200. 
A  piece  of  celluloid  was  placed  in  a  flask  heated  to  3200,  no  cavity 
being  left  in  the  plaster  to  receive  the  celluloid.  Closed  in  ten 
minutes.  It  sunk  a  bed  for  itself  in  the  hard  plaster,  flowing  but 
little.  This  is  a  hint  as  to  the  cause  of  misfits,  raised  bites,  and 
thickened  palates,  of  plates  molded  with  soft  plaster  and  low 
heats. 

"  8th  Series.  Testing  the  effects  of  quick  closing.  A  full  blank 
was  placed  in  a  full  flask  of  plaster  heated  to  3200,  and  closed  so 
that  the  halves  of  the  flask  came  together  on  one  side  consider- 
ably sooner  than  on  the  other.  Gave  it  over  fifteen  minutes  in  the 
oven.  When  opened  it  showed,  as  expected,  the  side  of  the  plate 
which  had  been  the  latest  closed  porous  and  brittle.  As  a  side 
issue  in  this  experiment,  tin-foil  of  two  thicknesses,  18  and  60,  were 
placed  side  by  side  on  the  blank,  and  when  peeled  off  the  surface 
below  was  of  a  browner  color  than  the  adjacent  celluloid. 

"  I  would  hint  at  the  possibility  of  the  celluloid  which  oozes 
from  the  flask,  and  touches  the  wall  of  the  oven,  being  ignited 
thereby  in  some  instances.  A  deep  excess-chamber  should  be 
cut  around  the  model  to  prevent  this.  Moreover,  this  escaped 
celluloid,  not  being  under  pressure,  is  doubtless  more  liable  to 
burn. 

"  Celluloid  hardens  on  being  subjected  to  dry  heat,  but  much 
of  this  is  not  desirable,  as  its  hardness  is  external,  while  inside- 
it  becomes  porous,  and  when  thus  hardened  is  very  brittle.  Cel- 
luloid will  burn  under  water,  as  demonstrated  in  a  vulcanizer,  at 
3200. 

'  Thin  edges  of  celluloid  will  soften  in  hot  drinks  in  the  mouth. 
Thus,  the  festoons  of  gum  left  thin  will  shrink  from  the  tooth,  pro- 


CELLULOID    BASE. 


349 


ducing  what  may  be  termed  a  free  edge  of  celluloid  gum,  under 
which  dirt  deposits,  and  shows  through  the  semi-translucent  cellu- 
loid. This  is  prevented  by  making  the  edges  of  the  festoons  of 
proper  thickness.  Another  error  frequently  seen  is  that  of  cutting 
away  the  interdental  celluloid  gum  (contrary  to  nature),  thus  form- 
ing cavities  difficult  to  cleanse  by  the  brush,  producing  unsightly 
discoloration  at  those  points. 

"  The  principal  objection  to  celluloid  is  that  after  a  year  or  two 
in  the  mouth  it  loses  its  beautiful  color,  and  becomes  of  a  dull 
vermilion  shade,  or  even  black.  This  will  probably  remain  the  chief 
objection  to  it.  That  it  is  not  so  tough  nor  so  elastic  as  vulcanite, 
and  that  in  consequence  it  wears  away  and  loses  its  smooth  surface 
in  the  mouth,  and  is  unfitted  for  clasps,  and  that  it  is  a  little  more 
difficult  to  work  than  rubber,  would  not  prevent  its  popularity,  if 
it  were  not  for  this  discoloration.  However,  the  loss  of  color  does 
not  always  extend  far  into  the  plate,  and  much  of  it  may  be  quickly 
removed  with  a  brush  wheel  and  pumice." 

Finishing. — This  is  accomplished  with  the  use  of  the  same 
instruments  used  in  rubber  cases.  The  final  polish  may  be  given 
first  with  pumice-stone,  and  afterward  with  whiting  or  Vienna  lime. 
Dr.  H.  D.  Knight  recommends  a  polish  obtained  by  rubbing  with 
an  old  cloth  wet  with  camphor.  This  may  be  valuable  between 
teeth  and  in  places  inaccessible  to  the  brush  wheel.  In  finishing, 
care  should  be  taken  not  to  heat  the  plate  by  friction,  as  by  so 
doing  the  surface  may  be  injured  or  the  plate  sprung  out  of  shape. 

VULCANITE  BASE-PLATE  FACED   WITH   CELLULOID. 

The  above  method  of  constructing  an  artificial  denture,  desig- 
nated by  the  inventor  as  the  "  new  mode  continuous-gum  "  proc- 
ess, provides  for  the  use  of  single  porcelain  teeth  without  artificial 
gums,  the  latter  being  represented  by  the  celluloid  facing.  This 
expedient  is  most  esteemed  by  those  who  regard  rubber  as  a  more 
suitable  material  for  a  base  than  celluloid,  and  who,  in  the  use  of 
the  former,  are  unable  to  meet  the  requirements  of  a  certain  class 
of  cases  with  either  single  gum  teeth  or  sectional  blocks. 

In  this  combination  work,  which  admits  of  an  optional  arrange- 
ment of  each  individual  tooth,  the  conditions  are  secured  which 
better  enable  the  operator  to  effect  such  arrangement  of  the  teeth 
as  will  best  serve  the  purposes  of  mastication  and  aid  in  restoring 


■?-0  MECHANICAL   DENTISTRY. 

the  customary  facial  contour  and  expression  of  the  individual. 
Still  other  advantages  are  claimed  for  this  method,  namely,  that 
the  rubber  is  stronger  and  more  elastic,  and,  being  harder,  the  pins 
are  less  liable  to  draw  or  loosen,  while  the  same  property  diminishes 
the  liability  to  mechanical  abrasion  of  the  palatal  surface  in  masti- 
cation, and.  lastly,  that  in  case  of  accident  to  the  teeth  they  may 
be  replaced  with  the  use  of  celluloid,  thus  obviating  entirely  the 
necessitv  of  revulcanizing,  a  process  which  always  impairs  the 
structural  integrity  of  the  rubber. 

The  first  step  in  the  process  of  constructing  this  kind  of  work 
consists  in  molding  the  rubber  base-plate,  with  the  teeth  attached. 
All  the  preliminary  processes,  including  the  arrangement  of  the 
teeth,  are  the  same  as  those  practised  when  rubber  alone  is  used. 
The  teeth  employed  are  those  manufactured  expressly  for  continu- 

FlG.   148. 


ous-gum  work  and  celluloid,  as  shown  in  Fig.  148.  In  waxing  up 
the  case,  all  the  exterior  surfaces  of  the  teeth  and  marginal  portions 
of  the  trial-plate  are  left  uncovered,  and  a  strip  of  wax  arranged 
all  along  the  external  border  of  the  wax  plate  to  form  a  groove  for 
the  celluloid,  as  shown  in  Fig.  148.  The  excavation  thus  formed 
exteriorly  should  extend  inwardly  into  the  interdental  spaces  far 
enough  to  secure  anchorage  for  the  celluloid  in  connection  with 
that  obtained  by  the  grooved  border.  The  space  or  spaces  for  the 
celluloid  facing  being  thus  provided  for,  the  palatal  portion  is 
properly  contoured,  the  case  flashed,  packed,  and  vulcanized  in  the 
usual  manner.  The  piece,  when  removed  from  the  flask,  will  ex- 
hibit an  undercut  groove  along  the  border,  and  the  external  portions 
of  the  crowns  and  roots  exposed  in  the  manner  shown  in  the  illus- 
tration. 

The  second   step  in   the  operation   consists  in   molding  the  cellu- 


CELLULOID    BASE. 


351 


loid  facing.  The  following  is  the  method  of  forming  the  matrix 
and  molding  the  celluloid :  Fill  up  all  the  space  between  the 
rimmed  border  of  the  plate  and  crowns  of  the  teeth  with  wax  and 
paraffin,  as  being  preferable  to  wax  alone,  and  then  contour  it 
exactly  as  required  in  the  finished  piece;  cover  with  tin-foil,  and 
stipple  the  surface  in  the  manner  heretofore  described.  The  case 
thus  prepared  is  ready  to  be  invested  for  the  purpose  of  obtaining 
the  matrix  in  which  to  mold  the  celluloid.  In  so  doing,  fill  the 
lower  section  of  the  flask  partly  with  plaster,  and  also  the  palatal 

Fig.   149. 


portion  of  the  plate,  and  then  place  the  latter  in  the  flask  with  the 
teeth  upward,  raising  the  front  part  of  the  plate  somewhat,  giving 
it  a  downward  inclination  posteriorly,  in  order  that  the  upper  sec- 
tion, when  the  investment  is  completed,  may  be  detached  without 
dragging.  The  plate  should  not  be  imbedded  in  the  plaster 
beyond  the  grooved  margin,  making  the  line  of  separation  on  the 
outside  along  the  border  from  heel  to  heel  of  the  plate.  Additional 
plaster  is  now  poured  in,  covering  the  entire  palatal  face  of  the 
plate  and  crowns  of  the  teeth,  leaving  only  the  outer  portions  of  the 


y^ 


MECHANICAL    DENTISTRY. 


latter  and  the  plate  exposed.  When  the  plaster  sets  somewhat, 
pour  in  more  plaster  around  the  inner  edge  of  the  flask  ring,  form- 
ing a  ridge,  and  also  a  corresponding  groove  or  space  between  it 
and  the  plate.  The  piece  thus  invested  will  present  the  appearance 
shown  in  Fig.  149.  The  surface  of  the  plaster  is  now  varnished, 
and  thin  oil  applied  to  all  the  surfaces.  When  the  wax  facing  is 
covered  with  tin-foil,  the  latter  should  not  be  oiled,  as  it  is  intended 
that  this  shall  adhere  to  the  plaster  when  the  flask  is  separated. 
The  investment  is  now  completed  by  adjusting  the  upper  section  of 
the  flask  and  filling  it  with  plaster.  When  sufficiently  hard,  the 
sections  are  carefully  separated  and  the  wax  thoroughly  removed 

Fig.  150. 


with  boiling  water.     The  tin-foil  will  remain  adherent  to  the  plaster 
in  the  upper  section. 

Select  a  celluloid  blank  of  suitable  size  and  saw  off  the  outer  rim, 
as  shown  in  Fig.  150.  Dress  and  carve  this  to  near  the  size  and 
form  of  the  space  to  be  filled,  having  some  excess  of  material. 
Having  first  softened  the  rim  thus  prepared  by  immersing  it  in 
boiling  water  for  a  few  moments,  press  it  well  into  the  space 
provided  for  it,  and  hold  there  until  rigid.  Place  the  two  sec- 
tions of  the  flask  together  in  their  proper  relation,  introduce  into 
the  oven  previously  heated,  and  close  the  flask  in  the  usual 
way.  When  the  piece  is  removed  from  the  flask,  and  the  tin-foil 
removed  by  peeling  it  from  the  surface,  to  which  it  will  adhere, 
little  will  be  required  in  the  way  of  finishing  except  to  remove 
surplus  material  at  the  necks  of  the  teeth  and  borders  of  the  plate, 


CELLULOID    BASE.  353 

and  final  smoothing  and  polishing  at  these  points.  If  the  facing 
material  has  been  stippled,  the  finished  piece  will  present  the  appear- 
ance shown  in  Fig.  151. 

The  above  process  is  also  applicable  to  gold  and  cast  metallic 
plates. 

ZYLONITE.* 

"  A  modified  form  of  celluloid  has  been  introduced  under  the 
name  of  zylonite,  the  working  results  of  which  appear  to  show  some 
difference  in  quality.  Zylonite,  like  celluloid,  is  composed  of 
pyroxylin  and  camphor,  but  in   different  proportions,  being,  it  is 

Fig.  151. 


claimed,   a   chemical   combination,   while   celluloid   is   a   mechanical 
mixture. 

"  Possessing  translucency,  the  effect  of  zylonite  in  the  mouth  is 
very  pleasing,  and,  so  far  as  it  has  been  tested,  promises  to  be  more 
durable  than  celluloid,  without  the  tendency  to  warp  or  to  change 
color  when  ordinary  care  is  taken  in  its  manipulation,  which  is  the 
same  as  for  celluloid.  The  zylonite  blanks  are  uniform  in  color, 
and  although  this  material  requires  the  same  amount  of  pressure  to 
mold,  it  flows  with  a  more  perfect  sharpness  of  outline  than  cellu- 
loid, and  apparently  does  not  disintegrate." 

*  Harris'  "  Principles  and  Practice  of  Dentistry." 


23 


CHAPTER  XXV. 

ATTACHING  PORCELAIN  TEETH   TO  A  METALLIC  BASE  WITH 
RUBBER  OR   CELLULOID. 

The  following  method  of  attaching  porcelain  teeth  to  a  metallic 
plate  by  means  of  rubber  or  celluloid,  though  but  little  practised 
heretofore,  is  attracting  more  attention  than  formerly,  and  is 
eminently  deserving  of  more  favorable  consideration  and  general 
adoption,  by  reason  of  its  conspicuous  and  acknowledged  merits, 
than  it  has  ever  yet  received.  The  credit  of  its  first  introduction 
to  the  notice  of  the  profession  is  due  to  Dr.  P.  G.  C.  Hunt,  of 
Indianapolis,  Ind.,  who  practised  the  method  as  early  as  1859,  anc^ 
whose  published  descriptions  of  the  manner  of  preparing  the  plate- 
base,  substantially  the  same  as  that  for  which  Mr.  S.  D.  Engle,  of 
Hazleton,  Pa.,  obtained  letters-patent  some  years  later,  were  given 
in  the  first  edition  of  this  work. 

That  it  possesses  marked  advantages  over  the  method  of  attach- 
ing teeth  to  a  metallic  plate-base  by  soldering  is  unquestionable. 
The  waste  and  consequent  change  in  the  form  of  the  plate  incident 
to  soldering,  so  inseparable  from  the  older  method  of  attachment 
by  means  of  stays  or  backings,  is  wholly  avoided ;  the  strain  upon 
the  platina  pins  is  greatly  lessened  by  reason  of  the  perfectly 
adapted  rubber  or  celluloid  socket  in  which  each  tooth  or  block 
securely  rests ;  the  liability  to  fracture  of  the  teeth  from  concus- 
sion or  violence  is  materially  diminished  on  account  of  the  pliable 
nature  of  the  attaching  material  used ;  a  near  approximation  to  the 
natural  form  of  the  ridge  or  gum  on  the  lingual  side  of  the  plate 
is  secured ;  the  rubber  or  celluloid,  penetrating  all  the  joints  and 
openings  between  and  beneath  the  teeth,  renders  the  piece  wholly 
impervious  to  the  oral  secretions,  making  it,  in  point  of  cleanliness 
and  purity,  equal  to  continuous-gum  work ;  the  facility  with  which 
injury  to  the  teeth  may  be  repaired;  the  practicability  of  remodel- 
ing the  piece  without  impairment  of  the  teeth  or  plate ;  its  suscep- 
tibility of  receiving  a  final  finish  excelled  by  no  other  method  in 
point    of    artistic    beauty; — these    are    among    the    qualities    which 

354 


METALLIC    BASE    WITH    RUBBER   ATTACHMENT.  355 

commend  this  method  of  substitution  as  one  of  peculiar  merit 
and  excellence. 

In  mounting  teeth  by  this  method,  preference  should  be  given  to 
either  gold,  platinum,  aluminium,  or  cast  metal  as  a  base.  When 
silver  is  used,  the  plate  should  be  made  from  refined  silver  alloyed 
with  platinum,  with  the  additional  precaution  of  interposing  a 
layer  of  tin-foil  between  the  rubber  and  plate,  an  expedient  not 
necessary  when  celluloid  is  employed.  Aluminium  has  a  limited 
adaptability  to  this  mode  of  substitution,  but  requires  special  treat- 
ment in  its  preparation  for  the  purpose,  a  description  of  which  will 
be  given  in  connection  with  the  manner  of  preparing  the  plate. 

The  manipulative  details  concerned  in  the  construction  of  an 
artificial  denture  by  the  method  under  consideration  are  thus  de- 
scribed by  Dr.  Hunt : 

"  Take  the  impression,  make  metallic  dies,  and  form  the  plate 
as  for  work  in  the  ordinary  way.  After  fitting  the  plate  in  the 
mouth,  get  the  articulation,  the  fullness  and  length  of  the  teeth, 
remove  the  wax  and  plate  from  the  mouth,  and  make  the  plaster 
articulation.  If  a  full  set,  after  separating  the  articulation,  and 
before  removing  the  wax  from  the  plate,  take  a  small,  light  pair  of 
dividers,  set  them  say  one  inch  apart,  and  with  one  point  following 
the  margin  of  the  wax,  representing  the  cutting  edge  of  the  teeth, 
and  the  other  point  marking  permanently  the  plaster,  you  have 
always  in  the  dividers  so  set  a  gage  for  the  length  of  any  par- 
ticular tooth.  A  convenient  substitute  for  the  dividers  may  be 
formed  from  a  piece  of  wire  of  convenient  length,  one-half  the 
diameter  of  a  common  excavator,  by  suitably  twisting  its  middle 
for  a  handle,  and  its  ends  being  sharpened,  and  pointing  in  the  same 
direction,  I  or  \}A  inches  apart. 

"  Thus  far  we  proceed  as  we  do  for  ordinary  gold  work.  We 
will  now  suppose  the  teeth  ground  and  jointed,  leaving  as  much 
space  between  the  teeth  and  plate  as  the  plate  will  admit  of.  We 
next  mark  with  a  sharp-pointed  instrument  on  the  labial  surface  of 
the  plate  each  point  where  it  is  necessary  to  place  a  loop  for  pur- 
poses hereinafter  described.  Then  apply  wax  to  the  external  or 
labial  parts  of  the  teeth  and  plate  in  any  manner  sufficient  to  retain 
the  teeth  in  position,  remove  the  wax  from  the  lingual  parts  of 
the  teeth  and  plate,  and  mark  the  position  on  the  metal  where  it 
is  desirable  to  insert  loops ;  remove  the  teeth  and  wax,  and  with  a 


356 


MECHANICAL    DENTISTRY, 


small  bow-drill  make  holes  through  the  plate  at  the  several  points 
previously  determined  on  for  the  attachments,  about  the  size  of  the 
ordinary  plate  punch-hole ;  take  a  wire,  or  ordinary  gold  plate,  cut 
in  strips,  say  from  a  half  to  one  line  in  width,  being  governed  by 
the  amount  of  room  there  is  under  the  base  of  the  teeth,  and 
with  small,  round-nosed  pliers,  bend  the  strip  around ;  grasp  both 
ends  with  square-nosed  pliers,  draw  the  round-nosed  pliers  from 
the  loop,  still  grasping  the  square-nosed  pliers  with  the  left  hand, 
and  with  a  hammer  strike  the  top  of  the  loop  a  sufficient  blow  to 
keep  the  ends  from  springing  apart.  Cut  off  the  ends,  and  dress 
down  to  fit  the  holes  in  the  plate,  after  which  solder  on  charcoal  or 
other  suitable  substance  without  investment." 


By  reference  to  Fig.  152,  which  illustrates  Mr.  Engle's  method 
of  providing  attachment  for  the  rubber  to  the  plate  by  means  of 
bent  wires  soldered  to  the  base,  the  substantial  identity  of  Dr. 
Hunt's  mode  of  forming  loops  for  the  same  purpose  will  be  apparent. 
With  this  digression,  we  return  to  Dr.  Hunt's  instructions : 
"Pickle,  dress,  and  polish  that  portion  of  the  plate  to  be  exposed 
to  view.  Bend  and  flatten  the  pins,  arrange  the  teeth  according  to 
the  articulation,  waxing  so  as  to  cover  up  the  loops  if  practicable; 
the  loops  should  be  placed  as  near  the  base  of  the  teeth  as  possible, 
the  rubber  forming  when  finished  a  part  of  that  general  concave 
shape  which  is  desirable  in  upper  dentures,  and  which  it  is  not  pos- 
sible to  obtain  with  the  ordinary  soldered  work.  Then  with  silicate 
of  soda  paint  the  joints,  to  keep  the  rubber  from  forcing  in  where 


METALLIC    BASE    WITH    RUBBER   ATTACHMENT.  357 

it  would  show  after  vulcanizing.  Flask,  vulcanize,  and  finish  up 
as  usual.  The  advantages  of  this  style  of  work  are  obvious. 
With  this  you  have  work  as  cleanly  as  the  continuous  gum,  de- 
cidedly more  so  than  the  very  best  single  gum  or  block-work  sol- 
dered in  the  usual  way;  again,  it  is  very  much  stronger,  less  liable 
to  breakage,  both  in  and  out  of  the  mouth,  as  the  rubber  gives  a 
perfect  base  and  support  for  the  teeth  to  set  upon.  By  this  method 
there  is  no  springing  of  plates.  As  your  plate  fits  the  mouth  when 
the  articulation  was  taken,  so  will  be  the  fit  when  the  case  is  com- 
pleted. 

"  On  the  labial  edge  of  the  upper  plate,  the  rubber  may  be  al- 
lowed to  project  beyond  the  edge,  if  desirable,  and  it  will  be  found 
in  many  cases  exceedingly  satisfactory  to  do  so,  and  allow  the  rub- 
ber to  be  of  considerable  thickness  near  the  alse  of  the  nose,  where 
the  loss  of  the  cuspidati  may  leave  a  want  of  support  to  the  soft 
parts  adjacent,  and  which  in  this  manner  can  be  readily  corrected. 
If  the  rubber  extends  upward  so  far  as  to  irritate  the  muscular 
structure,  a  few  minutes  will  be  sufficient  to  make  the  necessary 
alterations.  In  all  such  cases  where  we  have  control  of  our  patients, 
we  place  the  denture  in  the  mouth  before  finally  polishing,  so  as  to 
determine  as  accurately  as  possible  the  limit  to  which  extension 
upward  may  be  carried. 

"  The  neatest  work  on  this  principle  is  made  by  carving  blocks, 
giving  to  the  lingual  surface  that  regular  concave  form  which  is 
desirable.  In  this  no  platinum  pins  or  loops  are  necessary,  but  in 
that  half  of  the  matrix  on  which  the  blocks  are  carved,  large 
metallic  pins  are  so  arranged  as  to  be  hid  from  view  in  the  tooth 
body.  Different-sized  pins  may  be  used,  as  large  as  the  nature  of 
the  case  will  admit.  In  short,  we  make  the  holes  in  the  block 
similar  to  those  in  pivot  teeth,  where  there  is  not  sufficient  room 
in  the  block  above  the  tooth  (or  below  if  an  under)  to  allow  the 
pins  to  run  into  the  body  of  the  teeth.  After  burning,  grinding,, 
and  fitting,  get  the  position  of  the  holes  in  the  blocks  relative  to 
the  plate,  and  drill  through  the  plate  as  before,  and  instead  of 
loops,  solder  gold  wire  of  suitable  size  and  length,  sav  a  very 
little  shorter  than  the  depth  of  the  hole  in  the  blocks,  and  two- 
thirds  the  diameter  thereof ;  the  wire  should  have  a  screw-thread 
cut  on  it,  or,  that  which  is  just  as  good  and  more  expeditious,  barb 
or  cut  with  a  sharp  knife.     At  this  point  of  the  manipulation,  if  it 


3^8  MECHANICAL   DENTISTRY. 

is  desired  that  the  rubber  should  extend  beyond  the  labial  or 
buccal  edge  of  the  metallic  plate,  place  as  many  loops  at  different 
points  as  are  sufficient  to  retain  it  with  firmness,  after  which 
polish  the  plate,  wax,  and  proceed  as  before  described.  If  you 
desire  no  rubber  beyond  the  blocks,  the  roughness  of  the  holes  in 
the  same,  and  the  barbed  points  on  the  gold  wire,  when  properly 
packed  and  vulcanized,  will  give  ample  strength  and  firmness  to 
the  case,  and  if  care  has  been  used  in  the  entire  manipulation, 
you  will  have,  when  finished,  but  a  thin  line  of  rubber  exposed  to 
view. 

"  In  partial  cases,  if  of  gold  base,  solder  on  loops,  as  before,  for 
the  retention  of  the  teeth;  and  if  there  are  to  be  any  clasps,  make 
them  of  rubber,  uniting  them,  as  the  teeth,  with  loops.  If  the 
ordinary  plate  teeth  are  used,  it  is  frequently  necessary  to  back 
them  to  give  better  retaining-points  for  the  rubber.  If  blocks  are 
to  be  burned,  insert  loops  of  platinum  plate  in  the  shape  of  the  letter 
U  in  place  of  the  platinum  wire  pins.  In  consequence  of  the  affinity 
of  the  sulphur  in  the  vulcanite  for  silver,  plates  of  that  metal  should 
not  be  used." 

Another  method  of  increasing  the  attachment  between  the  metal- 
lic base  and  the  rubber,  is  that  of  spurring  the  plate  over  the  ridge 
with  a  sharp-pointed  chisel,  as  shown  in  Fig.  153. 

When  aluminium  is  employed  as  the  base,  the  strongest  and  alto- 
gether the  best  means  of  increasing  the  attachment  is  that  of  cutting 
or  punching  loops  from  the  plate  itself,  as  shown  in  Fig.  154.  Prob- 
ably the  best  instrument  for  this  purpose  is  that  devised  by  Dr.  J. 
H.  Gaskill,  which  is  illustrated  in  Fig.  155. 

When  a  cast  metal  plate  is  employed,  loops  or  pins  are  not 
needed,  as  sufficient  anchorage  is  secured  by  cutting  out  the  wax 
on  the  labial  surface  and  from  between  the  teeth  (in  fact,  from  every 
point  where  it  is  desirable  to  have  the  rubber)  before  Hashing  for  the 
casting  process.  After  the  plate  has  been  cast  and  finished,  the  rub- 
ber may  be  packed  and  the  case  reflasked,  vulcanized,  and  finished 
in  the  usual  manner. 

The  following  unique  and  original  method  of  casting  a  metal 
base-plate,  fastenings,  and  hooks,  in  a  single  piece,  is  thus  described 
by  Dr.  Xorman  W.  Kingsley :  "  The  plate  is  formed  of  a  thin  sheet 
of  wax  sel  up  on  the  plaster  model,  but  before  it  is  Masked  for  cast- 
ing I  take  a  dozen  small  gimp  tacks,  with  half  round  heads,  and  set 


METALLIC    BASE    WITH    RUBBER    ATTACHMENT. 


359 


them  in  a  row  upon  the  ridge  of  the  lower  jaw,  with  their  heads 
just  imbedded  in  the  wax,  and  then  flask  the  piece.  In  flasking  it, 
I  use  plaster  and  sand,  in  the  proportions  of  about  three  parts  of 
sand  to  one  of  plaster.  This  gives  a  fine  surface  when  it  comes  in 
contact  with  the  wax  in  making  the  mold,  and  it  is  sufficiently 
porous  to  dry  out  quickly.  When  the  flask  is  opened,  the  wax  is 
readily  removed ; '  the  tacks  are  pulled  out,  and  when  the  casting 


Fig.   153. 


Fig.    155. 


Fig.  154. 


is  made,  the  spaces  that  were  occupied  by  the  tacks  are  filled  with 
the  metal,  so  that  we  have  a  plate  with  a  row  of  tacks  of  the  same 
metal,  which  can  be  easily  bent  for  attachments,  standing  around 
upon  it." 

If  gum  sections  are  used  in  connection  with  a  plate  formed  in 
the  manner  just  described,  vulcanite  may  be  employed  as  a  means 
of  attachment,  but  plain,  single  teeth  are  equally  admissible  in  the 


360  MECHANICAL    DENTISTRY. 

use  of  either  rubber  or  celluloid.  The  particular  alloy  used  by  Dr. 
Kingsley  in  casting  plates,  and  of  which  he  speaks  in  terms  of  high 
commendation,  consists  of  pure  tin  and  bismuth,  in  the  proportion 
of  one  pound  of  the  former  to  one  ounce  of  the  latter. 

The  following  method  of  preparing  aluminium  plates  for  the  at- 
tachment of  the  rubber  was  communicated  to  the  author  by  Dr.  J. 
W.  Hollingsworth,  of  Greencastle,  Indiana,  an  intelligent  practi- 
tioner who  has  had  long  and  extended  practical  experience  in  the 
various  modes  of  working  this  metal  for  dental  purposes,  and  who 
says  of  the  following  mode  of  procedure  that  "  it  is  the  most  prac- 
ticable and  the  most  easily  manipulated  method  that  I  have  yet 
seen." 

The  following  is  the  manner  of  preparing  the  plate  as  described 
by  Dr.  Hollingsworth :  "  Perforate  the  ridge  of  the  plate  at  proper 
points  and  intervals ;  then  pass  through  these  perforations,  from  the 
inner  surface  of  the  plate,  headed  pins  made  of  aluminium,  which, 
after  replacing  the  plate  with  the  pins  back  upon  the  die,  we  shrink 
down  to  permanency  with  a  hollow  punch.  The  punch  must  be 
made  with  the  hole  not  quite  equal  in  depth  to  the  length  of  the  ex- 
truding portion  of  the  pins  and  slightly  bell-mouthed.  The  riveting 
process  forms  seriate  studs  or  pins,  which  may  be  bent  or  flattened 
with  pliers  in  any  way  to  suit  the  requirements  of  the  case." 

When  celluloid  is  used  for  purposes  of  attachment  in  the  case  of 
full  upper  dentures,  the  palatal  portion  of  the  blank  should  be  cut 
or  sawed  away,  leaving  only  the  ridge  portion  to  be  used,  and  this 
should  be  trimmed,  if  necessary,  so  as  to  have  but  little  excess  of 
material.  The  ordinary  full  blank  may  be  used  for  lower  cases, 
observing  the  same  precautions  in  regard  to  quantity  of  material. 
When  the  blank  is  thus  prepared,  the  subsequent  manipulations  are 
the  same  as  those  described  in  connection  with  the  celluloid  base. 

It  may  be  observed  that,  when  rubber  or  celluloid  is  used,  it  is 
better  to  dispense  with  the  plaster  model  in  forming  the  mold  or 
matrix,  and  proceed  as  follows:  When  the  teeth  are  arranged,  and 
the  required  contour  and  fullness  given  to  the  wax  drafts,  fill  the 
lower  section  of  the  flask  with  plaster,  and,  having  also  filled  the 
plate  with  the  same,  imbed  the  plate  in  it,  making  the  dividing  line 
on  the  external  rim  of  wax.  When  the  plaster  has  hardened,  and 
the   other    section    formed,    and    the   two   afterward    separated,    the 


METALLIC    BASE    WITH    RUBBER    ATTACHMENT.  361 

metallic  plate  will  remain  in  the  lower  section  and  the  teeth  in  the 
upper. 

When   using   celluloid,   plain   teeth   may   be  advantageously   em- 
ployed, the  former  representing  the  gum ;  this  gives  perfect  freedom 

in    the    arrangement    of    each    separate    tooth  in    the    denture,    an 

optional   disposition  the  importance  of  which  cannot  be  over-esti- 
mated. 


CHAPTER  XXVI. 
CAST  METAL  BASE. 

Cheoplastic  Process. — The  method  of  mounting  artificial  den- 
tures by  what  is  familiarly  known  as  the  "  cheoplastic  process,"  in 
which  the  base  consists  of  certain  metallic  compounds  or  alloys  in 
cast  form,  has  comparatively  but  limited  application  in  prosthetic 
practice.  The  method,  as  commonly  practised,  is  rarely  applied  to 
full  upper  cases,  occasionally  to  partial  upper  pieces,  but  chiefly  to 
lower  dentures  in  cases  of  unusual  absorption  of  the  alveolar  ridge, 
requiring  increased  weight  to  secure  adequate  stability  of  the  sub- 
stitute. The  alloys  in  most  general  use  for  this  purpose  are  those 
compounded  by  Drs.  Wood,  Weston,  and  Watt,  whose  names  are 
a  sufficient  guarantee  of  the  suitableness  of  those  several  alloys 
for  the  purpose. 

The  construction  of  a  denture  by  this  method  is  readily  accom- 
plished by  any  one  familiar  with  the  working  of  vulcanite  or  cel- 
luloid. The  manipulations  concerned  in  the  formation  of  a  mold 
or  matrix  are,  in  general,  the  same  as  those  employed  in  forming  a 
matrix  for  rubber  or  celluloid.  The  model  and  investing  material, 
however,  must.be  of  such  substances  as  maintain  their  integrity  of 
form  perfectly  under  the  heat  necessarily  applied  in  thorough 
drying  of  the  case  and  contact  of  molten  metals.  Simple  plaster, 
on  this  account,  is  unsuitable,  either  for  the  model  or  investment, 
and  it  is  customary,  therefore,  to  add  to  it,  in  relatively  large  pro- 
portions, such  substances  as  undergo  but  little,  if  any  change  of 
form  when  exposed  to  the  necessary  heat.  Those  most  commonly 
employed  are  finely-pulverized  pumice-stone,  marble-dust,  soap- 
stone  powder,  or  clean  white  sand.  Tn  the  use  of  any  of  these 
substances,  only  enough  plaster  should  be  added  to  give  to  the  mold- 
ing material  sufficient  body  or  strength  necessary  to  provide  against 
defacement  in  handling;  say  one  part  plaster  to  three  of  sand,  which 
is  the  mixture  generally  employed. 

One  of  the  best  adapted  flasks  for  molding  and  casting  purposes, 

362 


CAST    METAL   BASE. 


363 


contrived  by  Prof.  George  Watt,  is  exhibited  in  Fig.  156.  The 
piece,  properly  prepared  by  careful  contouring  of  the  wax  or 
paraffin,  is  then  flasked  in  the  same  manner  as  when  preparing  a 
mold  for  vulcanite.  When  the  sections  of  the  flask  are  separated, 
grooves  or  gateways  should  be  cut,  extending  from  the  posterior 
and  lateral  margins  of  the  mold  to  the  openings  on  either  side, 
shown  in  the  figure,  thus  providing  for  the  ingress  and  egress  of 
the  melted  metal  when  poured ;  after  which  all  traces  of  wax  should 
be  thoroughly  washed  out  with  boiling  water. 

The  sections  of  the  flask  are  now  adjusted  to  each  other,   and 
tightly    clamped,    to    prevent    the    escape    of    metal    when    poured. 


Fig.   156. 


Before  casting,  the  mold  should  be  thoroughly  dried  by  exposing 
it  for  two  or  three  hours  to  an  oven  heat,  and  the  temperature,  at 
the  moment  of  pouring,  should  be  raised  to  about  that  required  to 
fuse  the  alloys  mentioned,  or  about  400 °  to  440 °  F. 

In  pouring  the  metal  into  the  mold  through  one  of  the  lateral 
openings,  the  metal  should  rise  freely  and  quickly  into  the  opposite 
one,  and  if  bubbling  occurs,  which  will  never  happen  if  the  plaster 
has  been  sufficiently  dried,  the  flask  should  be  lightly  tapped  on 
some  hard  surface  until  the  ebullition  ceases,  thus  insuring  a  more 
certain  intrusion  of  the  metal  into  all  parts  of  the  mold  before 
solidification  takes  place. 


364 


MECHANICAL   DENTISTRY. 


Dr.  Weston  has  devised  a  casting  flask  (Fig.  157),  the  two  sec- 
tions of  which  form  an  encircling  band  with  the  sides,  or  top  and 
bottom,  open,  and  which  are  closed  securely  with  screw-bolts. 
This  form  facilitates  the  escape  of  moisture  from  the  plaster  invest- 
ment in  the  process  of  drying. 

When  the  piece  is  quite  cold,  it  may  be  readily  removed  from 


Fig.  157. 


tin-   flask   by   soaking  the  investing  material   for  a   few  minutes  in 
water. 

All  superfluous  metal  is  removed  with  suitable  instruments,  and 
;ill  surfaces  except  the  palatal  face  smoothed  and  polished,  first  with 
Scotch  stone  or  fine  emery  cloth,  and  finally  with  chalk  used  upon 
a  brush  wheel. 


CAST    METAL    BASE.  365 

If  there  are  any  narrow  spaces  or  interstices,  not  affecting  the 
integrity  of  the  plate,  that  are  not  completely  filled  at  the  time  of 
casting,  such  imperfections,  Dr.  Kingsley  suggests,  may  be  readily 
and  perfectly  repaired  with  amalgam. 

There  are  other  practicable  methods  by  which  cast  metallic  plates 
may  be  utilized  to  advantage,  and  their  application  to  the  needs  of 
the  practitioner  greatly  extended.  There  are  many  cases  of  ab- 
sorption in  which  a  lower  denture  constructed  entirely  of  cast 
metal  would  be  objectionable  on  account  of  excessive  weight. 
In  such  cases,  a  plate  of  sufficient  thickness  to  secure  the  required 
stability  may  be  cast,  and  the  teeth  subsequently  attached  with 
rubber  or  celluloid,  as  described  in  connection  with  swaged  plates ; 
or  the  base-plate  may  be  cast  in  the  form  of  the  rubber  base 
described  in  connection  with  the  new  mode  continuous  gum,  and 
faced  in  the  same  manner  with  celluloid — either  method,  while 
securing  the  requisite  weight,  admitting  also  of  the  use  of  single 
plain  teeth. 

GOLD  ALLOY  CAST  BASE. 

The  compound  of  gold,  silver,  and  tin,  in  varied  proportions,  in 
connection  with  specific  and  original  methods  of  casting  dental 
plates,  devised  and  patented  by  Dr.  George  F.  Reese,  of  Brooklyn. 
N.  Y.,  has  attracted  attention  as  a  possible  substitute  for  the  plastic 
vegetable  substances  so  commonly  employed  as  a  base  for  artificial 
dentures. 

After  premising  that  the  methods  in  common  use  for  casting 
alloys  were  not  applicable  to  one  having  the  molecular  properties 
of  Reese's  compound,  the  inventor  says  he  was  led,  after  multi- 
plied experiments,  to  adopt  the  plan  of  which  the  following  is  a 
description : 

The  impression  is  taken  with  plaster,  to  which  salt  or  sulphate 
of  potassa  has  been  added,  and  the  model  obtained  from  this  with 
pure  plaster.  Upon  this  the  teeth  are  arranged.  For  the  trial 
plate,  gutta-percha,  paraffin,  and  wax,  or  modeling  compound,  may 
~be  used.  When  satisfaction  in  the  occlusion  is  obtained,  then  the 
case  is  returned  to  the  model,  and  the  waxing  around  the  labial 
and  buccal  borders  of  the  teeth  completed.  That  portion  of  the 
trial  plate  which  covers  the  palatine  surface  is  now  removed,  so 
that  the  pins  of  the  teeth  will  be  nearly  exposed,  allowing  the  wax 


366  MECHANICAL   DENTISTRY. 

which  is  under  the  gum  to  remain.  That  the  plate,  after  casting,. 
shall  not  be  too  cumbrous,  the  trial  plate,  which  has  been  removed, 
must  be  substituted  with  two  thicknesses  of  French  flower  wax, 
cut  carefully  to  the  model,  and  pressed  down  closely  with  the 
finger  in  such  a  manner  that  no  wrinkles  will  appear  to  mar  the 
beauty  of  the  work. 

Fig.  158  represents  a  case  thus  prepared.  The  dotted  lines  show 
the  borders  of  the  thin  wax.  B,  A,  and  C,  represent  nipples  of 
solid  wax,  fixed  to  the  posterior  border  and  to  the  tuberosities,  A 
and  C  being  the  places  of  exit  for  the  molten  metal  into  the  waste 

Fig.  158. 


pockets,  and  B  the  place  of  entrance  of  the  metal  from  the  pouring- 
gain. 

The  case  is  now  transferred  to  the  small  brass  flask,  r,  Fig.  159,. 
the  sections  of  which  have  been  welj  oiled  upon  the  inner  surface,, 
to  facilitate  their  removal  from  the  investment.  Either  section  is 
then  placed  upon  a  plate  of  glass  and  plaster  poured  into  it  until 
half  filled.  The  model,  as  prepared,  after  being  well  saturated 
with  water,  is  imbedded  in  this  single  section,  allowing  the  teeth 
and  gums  to  remain  uncovered.  Set  on  the  counterpart  of  the- 
flask  and  add  more  plaster  along  the  posterior  border  until  the 
nipples  are  reached  or  slightly  covered.  After  this  has  set,  the 
upper  section  may  be  removed  and  the  surface  of  the  plaster 
covered   with   a  thin    varnish  or  soapy   water.     Return  the   section. 


CAST    METAL    BASE. 


367 


and  complete  the  investment.     Fig.  159  shows  the  case  thus  made 
ready. 

After  a  proper  time  place  the  flask  in  hot  water,  that  it  may  be 
separated  without  injury.  When  separated,  wash  away  all  the  wax, 
and,  by  means  of  gentle  tapping,  remove  the  flask  rings  from  the 
investment  and  set  them  aside.  The  depressions  formed  by  the 
nipples  may  now  be  extended  through  the  plaster  to  the  external 
edge;  or,  if  the  circumstances  of  the  case  make  this  impossible, 
the  channels  may  be  made  at  the  line  of  division  between  the  two 

Fig.  159. 


Case  Ready  for  the  Completion  of  Investment. 


sections,  as  shown  by  the  dotted  lines  in  Figs.  160  and  161. 
Externally,  the  channels,  D,  E,  F,  Fig.  161,  should  be  neatly 
countersunk  and  varnished  with  shellac  to  receive  the  pockets. 
The  latter  are  made  of  the  French  wax  by  warming  and  wrapping 
the  same  around  a  cone-shaped  stick  and  the  base  and  apex  of  the 
cone  neatly  trimmed  of  all  inequalities.  These  pockets  should  be 
about  iJ/2  inches  long,  and  about  ]/2  of  an  inch  in  diameter  at  the 
base,  and  %  of  an  inch  at  the  apex.  The  pouring-gain  is  made 
in  the  same  manner,  but  should  be  smaller  in  diameter  at  the  base 


368 


MECHANICAL   DENTISTRY. 


and  about  two  inches  long.  After  removing  these  wax  covers  from 
the  molding  sticks,  the  larger  ends  of  each  should  receive  a  thin 
wax  cover  secured  to  its  place,  and  made  water-tight  by  flowing 
hot  wax  along  the  line  of  junction,  after  the  manner  of  soldering. 
Trim  the  covers,  then  place  the  smallest  ends  of  the  large  cones 

Fig.   160. 


in  the  countersunk  channels  at  the  tuberosities  and  the  small  cone 
in  the  middle  hole,  and  secure  them  with  melted  wax.  Fig.  160, 
d' ,  e',  f ,  shows  the  pockets  thus  attached. 

Should  the  channels  have  been  made  through  the  solid  plaster 
of  the  lower  section,  as  in  Fig.  160,  then  the  upper  section,  Fig. 
161,  need  not  be  joined  to  it  until  after  the  pockets  are  secured  to 


CAST    METAL   BASE. 


369 


their  places.  Should,  however,  the  channels  have  been  made  upon 
the  line  of  division,  then  the  sections  must  be  joined  before  the 
pockets  can  be  attached. 

The  case  is  now  ready  for  a  second  investment,  which  is  done  in 
a  flask  sufficiently  large  to  embrace  the  case  as  it  now  presents. 
Fig.  162  represents  the  construction  of  the  large  flask.  One  section 
of  the  same  is  placed  upon  glass  and  about  half  filled  with  plaster. 
The  case,  having  been  well  soaked  with  cold  water,  is  laid  carefully 
upon  the  plaster,  allowing  the  long  cone  to  rest  in  the  notch  at  the 


Fig.  161. 


Upper  or  Counter  Section  corresponding  to  Fig.  160. 
for  entrance  and  exit  of  metal. 


D,  E,  F,  channels 


heel  of  the  flask,  and  the  waste  pockets  to  become  imbedded  in  the 
plaster.  Immediately  put  the  other  section  of  the  flask  in  place 
and  complete  the  investment  by  filling  with  plaster  the  uppermost 
section  to  fullness.  Of  course,  there  will  be  no  division  of  the  sec- 
tions, as  was  the  case  in  the  former  flasking.  After  solidification, 
the  pouring-gain  must  be  neatly  trimmed  and  countersunk,  and 
great  care  must  be  exercised  that  no  dirt  be  allowed  to  enter  the 
channel. 

The  wax,  which  is  imbedded  in  the  plaster,  and  which  forms 
the  waste  pockets,  will  be  entirely  absorbed,  and  no  trace  of  it  will 
be  seen  upon  opening  the  flask. 
24 


370 


MECHANICAL   DENTISTRY. 
Fig.  162. 


Fig.  163. 


— S 


CAST    METAL   BASE.  37 1 

All  is  now  ready  for  drying.  This  is  done  in  an  oven  specially 
prepared  for  the  purpose,  but  it  may  be  accomplished  in  any  way 
to  be  chosen  by  the  manipulator.  An  ice-cold  mouth  mirror 
placed  over  the  opening  of  the  pouring-gain  will  detect  the 
slightest  moisture  which  may  remain,  and  until  this  is  entirely 
dispelled  the  casting  should  not  be  attempted. 

There  are  several  grades  of  the  gold  alloy,  as  compounded  by 
Dr.  Reese,  to  melt  which  require  a  heat  registering  from  6oo°  to 
7000  F.,  but  a  higher  temperature  than  this  must  be  attained  before 
pouring,  in  order  to  secure  a  satisfactory  flow.  At  9000  rapid  oxida- 
tion takes  place.  This,  of  course,  should  be  avoided.  The  alloy 
may  be  melted  in  an  ordinary  iron  ladle  or  crucible,  over  a  gas  or 
other  flame,  and  should  be  poured  while  the  mold  is  hot. 

Fig.  164. 


After  the  lapse  of  an  hour  or  two,  or  until  the  cast  is  sufficiently 
cooled  to  insure  the  integrity  of  the  teeth,  it  may  be  placed  in  warm 
water,  when  the  investment  can  be  easily  removed. 

Fig.  163  represents  the  cast  after  removal.  The  surplus  metal 
may  be  separated  along  the  dotted  line  S,  with  a  ribbon  saw,  after 
which  the  denture  is  ready  for  the  pumice  wheel  and  brush.  Fig. 
164  represents  the  finished  case. 

Repairing. — The  process  of  repairing  broken  plates  is,  in  prin- 
ciple, the  same  as  above.  A  flask,  specially  constructed  by  the 
inventor,  is  used  for  this  purpose,  whereby  a  single  investment 
suffices.  Suppose,  for  example,  a  plate  is  broken,  from  the  labial  to 
the  posterior  border,  along  the  median  line;  the  broken  edges  are 
scraped  clean,  and  a  separation  made  of  about  ^  of  an  inch.  The 
parts  are  then  adjusted  upon  the  model,  and  the  space  between  the 


37^ 


MECHANICAL    DENTISTRY. 


approximate  edges  filled  with  wax.  At  each  extremity  of  the 
fissure  a  pencil  of  wax,  ]/§  of  an  inch  in  diameter,  and  l}4  inches 
long-,  is  securely  attached,  perpendicularly,  to  the  palatal  surface, 
and  the  whole  surrounded  with  plaster  to  the  depth  of  one  inch. 
Thus  will  be  constituted  two  sections,  which  are  separated,  and  the 
wax  washed  out.  The  external  ends  of  the  channels,  formed  by 
the  pencils,  are  then  countersunk,  and  into  each  is  inserted  a  wax 
cone,  the  one  forming  a  pouring-gain  and  the  other  a  waste 
pocket.  The  latter  should  be  entirely  covered  by  the  plaster. 
The  whole  is  now  invested  in  the  repair  flask,  and  subsequently 
submitted  to  the  process  of  drying. 

Dr.  W.  S.  Elliott,  of  New  York,  has  taken  advantage  of  the 
method  above  described  to  overcome  the  difficulties  attending  the 
construction  of  continuous-gum  work. 

To  maintain  a  perfect  adaptation  of  a  swaged  plate  seems 
almost  impossible,  in  consequence  of  the  springing  of  the  plate 
in  the  furnace.  To  avoid  this  difficulty,  the  following  plan  is 
suggested:  The  plaster  model  is  first  covered  with  two  thick- 
nesses of  French  flower  wax,  carefully  adjusted.  From  this  a 
metallic  die  and  counter-die  are  made,  and  a  very  thin  (No.  32) 
platina  plate  is  swaged  to  fit  the  waxed  model.  The  labial  border 
need  not  be  returned,  as  in  ordinary  cases.  Upon  this  the  teeth 
are  arranged,  and  the  case  is  transferred  to  the  furnace  for  biscuiting 
and  enameling.  After  proper  annealing,  it  is  replaced  upon  the 
model  and  waxed  up,  on  the  labial  and  buccal  borders,  over  the 
edge  of  the  plate,  then  flashed,  the  wax  removed,  and  the  metal 
cast  upon  it  in  the  manner  heretofore  described. 

Danger  of  checking  the  enamel  is  associated  with  the  process ; 
but  success  has  attended  the  effort,  and  it  is  hoped  that  further 
experiments  will  insure  perfect  and  uniform  results. 


CHAPTER   XXVII. 

DEFECTS  OF  THE  PALATAL  ORGANS  AND  THEIR  TREATMENT 
BY  ARTIFICIAL  MEANS. 

Palatine  Defects. — Defects  of  the  palatine  organs  may  be  divided 
into  two  classes,  viz.,  accidental  and  congenital.  The  first  includes 
all  loss  of  substance  in  either  hard  or  soft  palate  by  disease  or  other- 
wise. Such  defects  are  not  uniform  in  locality  or  extent,  being 
sometimes  but  a  simple  perforation  of  the  palate,  and  at  others  in- 
volving the  destruction  of  the  entire  soft  palate,  a  considerable  por- 
tion of  the  hard  palate,  the  vomer  and  turbinated  bones,  and  the  loss 
of  the  teeth. 

The  second  class  includes  all  malformations,  from  the  simple 
division  of  the  uvula  to  an  opening  through  the  velum,  palatine 
and  maxillary  bones,  and  a  division  of  the  upper  lip,  thus  uniting 
throughout  their  entire  extent  the  nasal  passages  with  the  oral 
cavity. 

These  malformations  are  quite  similar  in  character,  but  not  uni- 
form in  extent.  They  may  be  said  to  begin  with  the  uvula,  and  in 
the  uvula  and  velum  always  occupy  the  median  line;  but  as  the 
defect  progresses  anteriorly,  it  may  deflect  to  one  side  or  the  other 
of  the  vomer,  and  follow  the  nasal  passage  through  the  lips,  leav- 
ing the  vomer  articulated  with  the  palate  bone  on  one  side;  while 
in  other  cases  the  deformity  seems  to  follow  the  median  line,  and 
thus  involves  both  nasal  passages  and  terminates  in  a  double  fissure 
of  the  lip. 

In  both  cases,  accidental  and  congenital,  the  faculty  of  distinct 
articulate  speech  is  seriously  impaired  by  defects  of  any  extent. 
In  ordinary  cases  of  congenital  deformity,  deglutition  is  not 
materially  interfered  with.  The  patient,  having  never  known 
any  other  method  of  swallowing,  is  not  conscious  of  any  diffi- 
culty. Accidental  lesions,  however,  coming  generally  in  adult  life, 
produce,  in  this  respect,  very  great  inconvenience.  The  remedy 
for  these  evils  must  be  the   closing  of  the   abnormal   passage   by 

373 


374 


MECHANICAL   DENTISTRY. 


some  means  which  will  restore  the  functions  to  the  deformed 
organs.  In  perforations  of  the  hard  palate,  unless  of  extraordinary 
extent,  the  method  is  very  simple.  In  the  loss  of  the  soft  palate 
by  disease  the  remedy  is  more  difficult,  and  in  extensive  congenital 
deformity  still  more  complicated  appliances  will  be  required. 

As  we  have  classified  the  defects,  we  shall  also  classify  the  ap- 
pliances used  for  their  remedy. 

The  term  obturator  will  be  used  for  all  appliances  intended  to 
stop  a  passage,  or  all  openings  in  the  hard  or  soft  palate  which 
have  a  complete  boundary.  Appliances  made  to  supply  the  loss  of 
the  posterior  soft  palate,  whether  accidental  or  congenital,  will  be 
called  artificial  vela,  or  palates. 

Obturators. — Any  unnatural  opening  from  the  oral  cavity  into 
the  nasal  cavity,  which  will  permit  the  free  passage  of  the  breath, 
will  impair  articulation.  Any  appliance  which  will  close  such  pas- 
sage, and  can  be  worn  without  inconvenience,  will  restore  articula- 
tion.* Obturators  were  formerly  made  of  metallic  plate,  gold  or 
silver  being  most  commonly  employed,  and  many  very  ingenious 
pieces  of  mechanism  were  the  result  of  such  efforts,  but  latterly 
vulcanized  rubber  has  almost  entirely  superseded  the  use  of  metals. 
Vulcanite  has  been  found  preferable  to  metals,  being  much  lighter 
and  much  more  easily  formed  and  adapted,  particularly  when  of 
peculiar  shape. 

The  steps  to  be  taken  in  the  formation  of  an  obturator  are  not 
unlike  those  used  in  making  a  base  for  artificial  teeth.  It  is  essen- 
tial that  an  accurate  model  be  obtained  of  the  opening,  the  adjacent 
palatal  surface,  and  the  teeth,  if  any  remain  in  the  jaw.  For  this 
purpose  an  impression  in  plaster  is  the  only  reliable  means  for  such 
an  end.  Care  must  be  used  that  a  surplus  of  plaster  is  not  forced 
through  the  opening,  thus  preventing  the  withdrawal  of  the  im- 
pression by  an  accumulated  and  hardened  mass  larger  than  the 
opening  through  which  it  passed.  To  avoid  this,  beginners  or 
timid  operators  had  better  take  an  impression  in  the  usual  manner 
with   wax ;   if   this   is   forced   through,    it   can    be   easily    removed, 

*  The  student  will  bear  in  mind  that  no  cognizance  is  here  taken  of  openings 
similar  to  those  described  in  cases  of  congenital  fissure,  where  the  surgeon  has 
united  the  soft  palate,  and  left  an  opening  through  the  hard  palate,  to  be  covered 
by  an  obturator.  In  such  cases,  neither  the  surgeon's  operation  nor  the  obturator 
will  prove  of  much  advantage. 


ARTIFICIAL   TREATMENT   OF    PALATAL   DEFECTS. 


375 


without  injury  to  the  patient.  From  this  wax  impression  make  a 
plaster  model,  and  upon  this  form  an  impression-cup  of  sheet 
gutta-percha,  with  a  stick,  piece  of  wire,  strip  of  metal,  or  any  other 
convenient  thing  for  a  handle.  This  extemporized  impression-cup 
must  not  impinge  upon  the  borders  of  the  opening,  neither  should 
it  enter  to  any  extent.  With  a  uniform  film  of  soft  plaster,  of  from 
jL  to  x/%  of  an  inch  in  thickness,  laid  over  this  cup,  a  correct  impres- 
sion can  be  made  without  any  surplus  to  give  anxiety.  Upon  a 
correct  plaster  cast,  taken  from  such  an  impression,  make  a  model 
of  the  obturator  out  of  gutta-percha,  thin  sheets  of  modeling  com- 
pound, or  other  plastic  substance;  the  subsequent  steps  being  in 
principle  the  same  as  in  making  any  other  piece  of  vulcanite.  It 
is  desirable  that  it  should  enter  the  perforation  and  restore  as  far 
as  possible  the  lost  portion  of  the  palate,  but  it  must  not  protrude 
into  or  in  any  way  obstruct  the  nasal  passage. 

The  entire  freedom  of  the  nasal  passage  is  essential  to  the  purity 
of  articulation. 

That  portion  of  the  obturator  which  occupies  the  oral  cavity 
should  be  made  as  delicate  as  possible,  consistent  with  its  strength 
and  durability. 

A  clumsy  contrivance  will  interfere  with  articulation  almost  as 
much  as  it  is  improved  by  stopping  the  opening;  therefore,  if  the 
obturator  could  be  confined  entirely  to  the  opening,  like  a  cork  in 
a  bottle,  it  would  be  all  the  more  desirable,  but  as  it  cannot,  resort 
must  be  made  to  clasping  to  the  contiguous  teeth,  if  there  are  any, 
and  if  not,  the  obturator  must  spread  out  over  the  whole  jaw,  and 
receive  its  support  in  the  same  manner  as  would  a  set  of  artificial 
teeth.  In  fact,  this  is  just  what  it  would  become  in  such  a  case, 
viz.,  an  upper  set  of  teeth  bridging  over  and  filling  up  an  opening 
in  the  palate,  thus  combining  an  obturator  with  a  set  of  teeth. 

Kingsley's  Obturators  and  Methods  of  Procedure. — The 
following  descriptions,  with  accompanying  illustrations,  were  con- 
tributed to  this  work  by  Professor  Norman  W.  Kingsley,  who 
excels  in  the  practice  of  this  difficult  and  important  specialty  of  the 
dental  art. 

Fig.  165  represents  an  obturator  without  teeth  and  without 
clasps,  for  a  perforation  of  the  hard  palate,  being  sustained  in  situ 
by  impinging  upon  the  natural  teeth  with  which  it  comes  in  con- 
tact.    Accuracy  of  adaptation  and  delicacy  in  form  are  all  that  is 


3/6 


MECHANICAL   DENTISTRY. 


essential  in  such  cases,  and  the  restoration  of  the  speech  will  follow 
immediately. 

Fig.  1 66  represents  a  more  complicated  obturator,  adapted  to  an 
opening-  in  the  soft  palate. 

The  necessity  for  a  variation  in  the  plan  will  be  found  in  the 
anatomical  fact  of  the  constant  muscular  action  of  the  soft  palate, 
which  would  not  permit,  without  irritation,  the  presence  of  an  im- 
movable fixture. 

This  is  contrived,  therefore,  with  a  joint  that  will  permit  the  part 
attached  to  the  teeth  to  remain  stationary,  while  the  obturator 
proper  is  carried  up  or  down  as  moved  by  the  muscles.  The 
joint,  A,  should  occupy  the  position  of  the  junction  of  the  hard 
and  soft  palates.     The  joint  and  principal  part  of  the  appliance  is 


Fig.  166. 


made  of  gold,  the  obturator  of  vulcanite.  The  projection,  B,  lies 
like  a  flange  upon  the  superior  surface  of  the  palate  and  sustains 
it;  otherwise  the  mobility  of  the  joint  would  allow  it  to  drop  out 
of  the  opening.  This  flange  is  better  seen  in  the  side  view  marked 
C.  It  is  readily  placed  in  position  by  entering  the  obturator  first, 
and  carrying  the  clasps  to  the  teeth  subsequently. 

Figs.  165  and  166  will  illustrate  the  essential  principles  involved 
in  all  obturators.  The  ingenuity  of  the  dentist  will  often  be  taxed 
in  their  application,  as  the  cases  requiring  such  appliances  all  vary 
in  form  and  magnitude. 

Artificial  Palates. — Before  proceeding  to  a  description  of 
appliances,  a  brief  reference  to  the  anatomical  relations  and  func- 
tions of  the  palate  will  be  necessary.     The  palate  exercises  quite 


ARTIFICIAL   TREATMENT    OF    PALATAL    DEFECTS. 


377 


as  important  an  office  in  the  articulation  of  the  voice  as  does  the 
tongue  or  lips.  Being  a  muscular  and  movable  partition  to  sep- 
arate the  nasal  and  oral  cavities,  one  edge  is  attached  to  the  border 
of  the  hard  palate,  while  the  other  vibrates  between  the  pharynx 
and  the  tongue.  The  voice,  therefore,  as  it  issues  from  the  larynx, 
is  directed  by  the  palate  entirely  into  the  mouth,  or  through  the  nose, 
or  permitted  to  pass  both  ways. 

A  very  slight  deviation  in  this  organ  from  its  natural  form  will 
make  the  voice  give  a  different  sound.  So  will,  also,  the  presence 
of  anything  that  clogs  the  natural  passages,  either  oral  or  nasal. 

Place  any  obstruction   in   the  nasal   passages,   paralyze  the   soft 

Fig.  167. 


palate,  or  let  it  be  deficient  in  size,  and  the  power  of  distinct  articu- 
lation is  wanting. 

The  evidence  of  this  statement  is  frequently  found  after  the 
surgeon  has  successfully  performed  the  operation  of  staphylor- 
rhaphy in  cases  of  congenital  fissure. 

In  such  instances,  with  rare  exceptions,  the  newly  formed  palate 
is  so  deficient  in  length,  and  so  tense,  as  to  be  deprived  of  its  func- 
tion. It  cannot  be  raised  so  as  to  meet  the  pharynx  and  shut  off 
the  nasal  passage,  but  hangs  like  an  immovable  septum  to  divide  the 
column  of  sound. 

Fig.  167  represents  a  defective  palate  belonging  to  the  first  class, 
the  uvula  and  a  portion  of  the  soft  palate  contiguous  being  de- 


3/8  MECHANICAL   DENTISTRY. 

stroyed  by  disease.  In  such  a  case  an  obturator  would  be  useless ; 
the  constant  activity  and  the  surrounding  parts  would  not  tolerate 
it.  The  material  used  for  a  substitute  must  be  soft,  flexible,  and 
elastic,  and  the  elastic  vulcanite  is  admirably  adapted  to  this  pur- 
pose. 

By  observing  the  cut  (Fig.  167)  it  will  be  seen  that  a  portion  of 
the  soft  palate  along  the  median  line  remains,  and  consequently 
there  will  be  considerable  muscular  movement  which  must  be 
provided  for,  and  which  may  be  taken  advantage  of.  It  is  desir- 
able to  make  this  movement  available  in  using  an  artificial  palate, 
as  thereby  more  delicate  sounds  are  produced  than  otherwise. 

This  case  presents  some  extraordinary  difficulties  in  the  fact 
that  all  the  teeth  of  the  upper  jaw  have  been  extracted,  and  it  was 

Fig.  168. 


necessary,  therefore,  to  adopt  a  plate  which  should  not  only  sustain 
teeth  for  mastication,  but  bear  the  additional  responsibility  of 
supporting  the  artificial  palate.  In  the  choice  of  material  best 
adapted  for  the  base  for  the  teeth  in  such  instances,  it  is  preferable 
to  adopt  that  which  will  prove  the  most  durable.  There  are  too 
many  interests  involved  to  risk  the  adoption  of  anything  but  the 
best.  In  the  case  under  description,  the  patient  desired  duplicates, 
and  two  sets  of  teeth  were  made,  one  on  gold  and  the  other  on 
platina,  with  continuous  gum. 

The  plates  were  made  like  other  sets  of  teeth,  with  the  excep- 
tion of  a  groove  located  on  the  median  line  at  the  posterior  edge 
to  receive  the  attachment  for  the  palate  (marked  C,  in  Fig.  168). 

Fig.  168  will  indicate  the  set  of  teeth  with  palate  attached.  The 
wings  marked  letters  A  and  B  are  made  of  soft  rubber;  the  frame 


ARTIFICIAL   TREATMENT    OF    PALATAL   DEFECTS.  379 

to  support  them  is  made  of  gold,  with  a  joint  to  provide  for  the 
perpendicular  motion  of  the  natural  palate,  as  in  the  case  of  the 
obturator  represented  in  Fig.  166. 

When  the  artificial  palate  is  in  use,  the  joint  and  frame  imme- 
diately contiguous  lie  close  to  the  roof  of  the  mouth ;  the  rubber 
wing,  letter  A,  bridges  across  the  opening  on  the  inferior  surface,  or 
side  next  the  tongue ;  the  wing,  letter  B,  bridges  across  the  opening 
on  the  superior  or  nasal  surface,  and  is  also  prolonged  backward  until 
it  nearly  touches  the  muscles  of  the  pharynx  when  they  are  in  repose. 

Both  these  wings  reach  beyond  the  boundary  of  the  opening 
and  rest  on  the  surface  of  the  soft  palate  for  a  distance  of  from  y% 
to  54  of  an  mcn>  thus  embracing  the  entire  free  edge  of  the  soft 
palate.  This  last  provision  enables  the  natural  palate  to  carry  the 
artificial  palate  up  or  down,  as  articulation  may  require. 

When  the  organs  of  speech  are  in  repose,  there  is  an  opening 
behind  the  palate  sufficient  for  respiration  through  the  nares. 
When  these  organs  are  in  action,  a  slight  elevation  of  the  palate, 
•or  a  contraction  of  the  pharynx,  will  entirely  close  the  nasal  pas- 
sage and  direct  all  the  voice  through  the  mouth.  The  palate  thus 
becomes  a  valve  to  open  or  close  the  nares,  and  to  be  tolerated 
must  be  made  with  thin  and  delicate  edges  which  will  yield  upon 
pressure.  An  instrument  thus  made  will  restore,  as  far  as  is  pos- 
sible by  mechanism,  the  functions  of  the  natural  organ. 

In  the  case  under  description  the  patient  was  a  lady;  the  defect 
had  existed  for  seven  years  before  remedy.  Articulation  was  very 
defective;  distinct  and  perfect  articulation  followed  within  one 
month. 

Fig.  169  represents  the  artificial  palate  separated  into  its  con- 
stituent parts.  The  frame  is  bent  at  the  joint,  in  the  engraving,  to 
show  a  stop,  marked  D,  which  prevents  the  appliance  from  drop- 
ping out  of  position.  Letter  C  shows  the  tongue,  which  enters  the 
groove  in  the  plate  of  teeth  and  connects  them.  Letters  A  and  B 
are  the  rubber  flaps,  which  are  secured  to  the  frame  by  the  hooks,  as 
seen  in  the  engraving. 

The  process  for  making  the  rubber  wings  will  be  found  described 
on  page  385. 

Fig.  170  shows  a  more  extensive  palatine  defect  of  the  first  class. 
In  this  case  the  entire  soft  palate  is  gone,  together  with  a  small 
portion  of  the  hard  palate  at  the  median  line. 


38o 


MECHANICAL    DENTISTRY. 


Although  this  defect  is  greater  in  extent,  the  means  for  its  remedy 
are  more  simple.  The  muscles  of  the  palate  are  entirely  gone,  and 
consequently  no  perpendicular  movement  need  be  provided  for. 

Fig.  169. 


The  appliance  in  this  case  will  resemble  an  elastic  obturator 
more  than  the  valve-like  palate  of  the  preceding  one.  The 
principle  here  adopted  will  be  substantially  that  recommended 
by  Mr.   Sercombe,  of  London,  and  consists  of  a  plate  with  a  set 

Fig.  170. 


of  teeth  in  the  usual  form,  and  attached  to  its  posterior  edge  an 
apron  of  soft  rubber,  which  shall  bridge  the  opening  on  its  in- 
ferior surface,  extending  nearly  to  the  pharynx.    Fig.    171    repre- 


ARTIFICIAL   TREATMENT    OF    PALATAL   DEFECTS. 


33l 


sents  the  set  of  teeth  with  the  palate  attached.  In  Mr.  Sercombe's 
appliance  this  apron  was  made  of  the  common  sheet  rubber  in 
the  market,  prepared  for  other  uses,  and  is  objectionable  for  two 
reasons :  First,  a  want  of  purity  in  the  materials  of  which  it  is  com- 
pounded, in  many  instances  substances  being  used  in  its  manufacture 
which  would  prove  deleterious  to  the  health  of  the  patient;  and, 
second,  its  uniformity  of  thickness.  It  is  far  preferable,  therefore. 
to  make  a  mold  which  will  produce  a  palate  of  pure  and  harmless 
materials,  and  which  shall  be  of  sufficient  thickness  in  the  central  part, 
and  at  its  anterior  edge,  to  give  it  stability,  and  shall  have  a  thin 
and  delicate  boundary  wherever  it  comes  in  contact  with  movable 

Fig.   171. 


tissue.  Such  a  palate  may  be  made  in  a  mold  by  substantially 
the  same  process  as  hereinafter  described.  (See  page  386.)  It 
may  be  secured  to  the  plate  by  a  variety  of  simple  means.  One, 
which  will  give  as  little  trouble  to  the  patient  as  any  other, 
is  to  make  a  series  of  small  holes  along  the  edge  of  the  plate 
and  stitch  it  on  with  silk;  or  fine  platina,  gold,  or  silver  wire  may 
be  used. 

It  is  desirable  to  have  the  plate  and  palate  present  a  uniform 
surface  on  the  lingual  side.  In  fitting  the  plate,  therefore,  it  mav 
be  raised  along  the  posterior  edge  from  Jg  to  -^  of  an  inch, 
according  to  the  thickness  of  palate  desired.     The  rubber  will  thus 


382  MECHANICAL   DENTISTRY. 

be  placed  on  the  palatine  surface  of  the  plate  and  present  uniformity 
on  the  lingual  surface. 

A  little  thought  will  show  that  in  this  case  the  patient  must  edu- 
cate the  muscles  of  the  pharynx  alone  to  do  the  work  of  shutting  off 
the  nares,  which  in  the  former  case  was  performed  by  them  in  con- 
junction with  the  muscles  of  the  palate.  Perfection  of  articulation 
will  therefore  depend  upon  the  success  of  the  patient  in  this  new 
use  of  these  muscles. 

In  cases  of  accidental  lesions  of  the  palate,  such  as  are  under 
consideration,  this  education  of  the  muscles  to  a  new  work  will 
not  be  difficult.  The  patient  at  some  former  time  has  had  the 
power  of  distinct  articulation;  his  ear  has  recognized  in  his  own 
voice  the  contrast  between  his  present  and  former  condition ;  the 
ear  will  therefore  direct  and  criticize  the  practice  until  the  result 
is  attained. 

In  the  case  illustrated  by  Figs.  170  and  171,  the  defect  had  ex- 
isted for  twenty-eight  years,  the  patient  at  the  time  of  the  intro- 
duction of  the  artificial  palate  being  nearly  fifty  years  of  age.  The 
effect  upon  the  speech  was  instantaneous.  Articulation  was  im- 
mediately nearly  as  distinct  as  in  youth,  and  this  remarkable  dis- 
tinctness can  only  be  accounted  for  upon  the  assumption  that  the 
pharyngeal  muscles  had  undergone  a  thorough  training  in  the  vain 
effort  to  articulate  without  any  palate.* 

The  two  cases  chosen  to  illustrate  the  application  of  artificial 
palates  in  accidental  lesion  have  required,  as  will  have  been  per- 
ceived, entire  upper  sets  of  artificial  teeth  in  connection  with  the 
palates.  This  selection  was  purposely  made,  because  the  difficul- 
ties to  be  overcome  are  much  greater.  In  cases  where  there  are 
natural  teeth  remaining  in  the  upper  jaw,  the  palate  and  its  connec- 
tion with  a  plate  would  be  substantially  the  same,  and  the  plate 
might  easily  be  secured  to  the  teeth  by  clasps,  in  the  same  manner 
as  a  partial  denture. 

Artificial  Palates  for  Congenital  Fissure. — Congenital  fissure 
of  the  palate  presents  far  greater  difficulties  to  be  overcome  than 
cases  of  accidental  lesion.  The  opening  is  commonly  more  exten- 
sive, the  appliance  more  complicated,   and  the  result  more  prob- 


*  An  account  of  this  case  appears  in  the  Argus,  of  Bainbridge,  Georgia,  August 
1,  1868,  written  by  the  patient  himself,  the  editor  of  that  paper. 


ARTIFICIAL   TREATMENT    OF    PALATAL   DEFECTS.  383 

lematic.  Nevertheless,  appliances  have  been  made  in  a  large  number 
of  cases  which  have  enabled  the  wearer  to  articulate  with  entire 
distinctness,  so  much  so  as  not  in  the  least  to  betray  the  defect. 
The  first  efforts  in  this  direction  were  of  the  character  of  obturators, 
simply  plugs  to  close  the  posterior  nares,  and  the  results  were  far 
from  satisfactory.  It  was  not  until  it  was  recognized  that  the  two 
classes  of  cases,  accidental  and  congenital,  were  entirely  distinct  that 
much  progress  was  made. 

Nearly  every  case  of  accidental  lesion  can  be  treated  with  an 
obturator  with  considerable  success;  very  rarely  will  an  obturator 
be  of  any  benefit  in  congenital  fissure,  even  if  the  congenital  and 
accidental  case  present  substantially  the  same  form  of  opening. 
For  this  reason  so  much  mystification  has  been  thrown  around 
these  appliances  within  a  few  years  past.  The  character  of  the 
different  classes  has  been  confounded,  and  an  instrument  admirably 
adapted  to  one  class  has  had  claimed  for  it  an  equal  application  to 
the  other  class.  Let  it  be  understood,  therefore,  as  a  rule  to  which 
there  will  be  but  few  exceptions,  that  congenital  fissure  of  the  soft 
palate  requires  for  its  successful  remedy  a  soft,  elastic,  and  mov- 
able appliance,  and  that  when  the  most  skilfully  made  and  adapted 
instrument  is  worn,  articulation  must  be  learned,  like  any  other 
accomplishment.  Various  inventions  have  been  made  for  this 
purpose  within  the  last  twenty-five  years,  from  the  most  compli- 
cated one  of  Mr.  Stearns,  described  in  the  first  edition  of  this  work, 
to  the  extreme  of  simplicity  of  bridging  the  gap  with  a  simple  flap 
of  rubber.  The  Stearns  instrument,  with  all  its  complexity,  em- 
bodied the  only  true  principle,  viz.,  the  rendering  available  the 
muscles  of  the  natural  palate  to  control  the  movements  of  the  arti- 
ficial palate. 

The  essential  requisites  of  an  artificial  palate  will  be  to  restore, 
as  far  as  possible,  the  natural  form  to  the  defective  organs  with  such 
material  as  shall  restore  their  functions.  Muscular  power,  certainly, 
cannot  be  given  to  a  piece  of  mechanism,  but  the  material  and  form 
may  be  such  that  it  will  yield  to  and  be  under  the  control  of  the 
muscles  surrounding  it,  and  thus  measurably  bestow  upon  it  the 
function  of  the  organ  which  it  represents. 

Fig.  161  represents  a  model  of  a  fissured  palate,  complicated 
with  harelip  on  the  left  side  of  the  mesial  line.  There  is  a  divi- 
sion, also,  of  the  maxilla  and  the  alveolar  process,  the  sides  being 


3§4 


MECHANICAL   DENTISTRY. 


covered  with  mucous  membrane,  which  come  in  contact  with  each 
other  but  are  not  united.  The  left  lateral  incisor  and  left  canine 
tooth  are  not  developed. 

Fig.  173  represents  the  artificial  velum,  as  viewed  from  its  supe- 

Fig.  172. 


rior  surface,  together  with  the  attachment  and  two  artificial  teeth 
to  fill  the  vacancy. 

The  lettered  portion  of  this  appliance  is  made  of  soft  vulcanized 

Fig.  173. 


rubber;  its  attachment  to  the  teeth  of  hard  vulcanized  rubber,  to 
which  the  velum  is  connected  by  a  stout  gold  pin,  firmly  imbedded 
at  one  end  in  the  hard  rubber  plate.  The  other  end  has  a  head, 
marked  C,  which,  being  considerably  larger  than  the  pin,  and  also 


ARTIFICIAL   TREATMENT   OF    PALATAL   DEFECTS. 


385 


than  the  corresponding  hole  in  the  velum,  is  forced  through — the 
elasticity  of  the  velum  permitting — and  the  two  are  securely  con- 
nected. 

The  process,  B,  laps  over  the  superior  surface  of  the  maxilla 
(the  floor  of  the  naris),  and  effectually  prevents  all  inclination  to 
droop. 

The  wings,  A  A,  reach  across  the  pharynx,  at  the  base  of  the 
chamber  of  the  pharynx,  behind  the  remnant  of  the  natural  velum. 

The  wings,  D  D,  rest  upon  the  opposite  or  anterior  surface  of 
the  soft  palate. 

Fig.  174. 


Fig.  174  represents  a  model,  the  same  as  Fig.  172,  with  the  ap- 
pliance, Fig.  173,  in  situ. 

The  wing,  D  D,  in  Fig.  173,  and  the  posterior  end  of  the  arti- 
ficial velum  only  in  this  cut  being  visible. 

Method  of  Making  an  Artificial  Palate. — The  success  of  these 
appliances  depends  very  much  upon  the  accuracy  of  the  model 
obtained  to  work  by. 

It  is  essential  that  the  entire  border  of  the  fissure,  from  the  apex 
to  the  uvula,  should  be  perfectly  represented  in  the  model,  as  the 
parts  are  when  in  repose.  It  is  also  necessary  that  the  model  show 
definitely  the  form  of  the  cavity  above,  and  on  either  side  of  the 
opening  through  the  hard  palate,  being  that  part  of  the  cavity  which 

25 


386  MECHANICAL   DENTISTRY. 

is  hidden  from  the  eye.  It  is  desirable,  also,  that  the  posterior  sur- 
face of  the  remains  of  the  soft  palate  be  shown,  but  this  is  not 
essential ;  but  it  is  especially  important  that  the  anterior  or  under 
surface  be  represented  with  relaxed  muscles  and  in  perfect  repose. 
The  impression  for  such  a  model  must  be  taken  in  plaster;  it  is 
the  only  material  now  in  use  adapted  to  the  purpose.  An  ordinary 
Britannia  impression-cup  may  be  used,  selecting  one  in  size  and 
form  corresponding  to  the  general  contour  of  the  jaw.  This  cup 
will  be  found  too  short  at  the  posterior  edge  to  receive  the  soft 
palate,  but  it  may  be  extended  by  the  addition  of  a  piece  of  sheet 
gutta-percha,  which  must  be  molded  into  such  form  as  not  to  im- 
pinge upon  the  soft  palate,  but  which  will  reach  under  and  beyond 
the  uvula,  and  thus  protect  the  throat  from  the  droppings  of  plaster. 
Before  using  the  plaster  the  posterior  edge  of  the  gutta-percha 
extension  may  be  softened  by  heat  and  introduced  into  the  mouth ; 
contact  with  the  soft  palate  will  cause  it  to  yield,  so  that  there  is 
no  danger  of  its  forcing  away  the  soft  tissues  when  the  plaster  is 
used.  With  the  precaution  not  to  use  too  much  plaster,  the  first 
effort  will  be  to  get  only  the  lingual  surface.  After  trial,  if  the 
impression  show  definitely  the  entire  border  of  the  fissure,  and  the 
soft  palate  has  not  been  pushed  up  by  contact  with  the  cup,  nor 
pulled  up  by  the  spasmodic  action  of  the  levator  muscles,  it  is  all 
that  is  thus  far  desired.  If,  however,  the  soft  parts  have  been  dis- 
turbed (which  on  close  comparison  a  little  experience  will  decide), 
it  is  better  to  cast  a  model  into  the  impression,  and  upon  this 
model  extemporize  an  impression-cup.  This  temporary  cup  will 
have  the  advantage  of  the  former,  insomuch  that  it  will  require 
but  a  film  of  plaster  to  accomplish  the  result,  thus  lessening  the 
danger  of  disturbing  the  soft  tissues.  After  the  removal,  if  it  is 
seen  that  any  surplus  has  projected  through  the  fissure  and  lapped 
out  to  the  floor  of  the  nares,  it  may  be  pared  off. 

The  next  step  will  be  to  obtain,  in  conjunction  with  this  impres- 
sion of  the  under  surface,  which  we  will  call  the  palatal  impression, 
an  impression  of  the  upper  or  nasal  surface  of  the  hard  palate. 

This  can  be  done  by  filling  the  cavity  above  the  roof  of  the 
mouth  with  soft  plaster  down  to  the  border  of  the  fissure,  and 
while  yet  very  soft  carrying  immediately  the  palatal  impression 
against  it,  and  retaining  it  in  that  position  until  the  plaster  is  hard, 
which  can  easily  be  ascertained  by  the  remains  in  the  vessel  from 


ARTIFICIAL   TREATMENT    OF    PALATAL   DEFECTS.  387 

which  it  was  taken.  With  the  precaution  to  paint  the  surface  of 
the  palatal  impression  with  a  solution  of  soap,  to  prevent  the  two 
masses  from  adhering  when  brought  in  contact,  there  will  be  no 
difficulty  in  removing  it  from  the  mouth,  leaving  the  mass  which 
forms  the  nasal  portion  in  situ.  With  a  suitable  pair  of  tweezers 
this  mass  is  easily  carried  backward  and  withdrawn  from  the 
mouth,  and  the  irregular  surface  of  contact  indicates  its  relation  to 
its  fellow  when  brought  together. 

The  method  of  obtaining  the  model  of  the  jaw  from  the  im- 
pression does  not  require  any  particular  description.  The  process 
is  similar  to  the  making  of  a  cast  in  any  other  mouth  impression. 

The  model  represented  in  Fig.  172  shows  a  convenient  form  for 
such  a  cast. 

When  the  nasal  portion  of  the  impression  does  not  indicate  the 
superior  surface  of  the  soft  palate,  the  part  may  be  represented  in 
the  cast  by  carving.  It  is  not  essential  to  the  success  of  the  instru- 
ment to  be  made  that  the  posterior  surface  of  the  soft  palate  should 
be  represented  with  the  same  accuracy  that  is  required  of  the 
inferior  surface,  or  of  both  surfaces  of  the  hard  palate.  By  the  aid 
of  a  small  mirror  and  a  blunt  probe,  the  thickness  of  the  velum 
and  the  depth  behind  the  fissure  can  be  ascertained,  and  the  model 
carved  accordingly. 

The  portion  of  the  artificial  palate  coming  in  contact  with  it  is 
so  elastic  that  it  easily  adapts  itself  to  a  slight  inequality,  rendering 
absolute  accuracy  less  important. 

The  next  step  will  be  the  formation  of  a  model  or  pattern  of  the 
palate.  Sheet  gutta-percha  is  preferable  for  this  purpose,  although 
wax,  or  many  other  plastic  substances,  might  answer. 

The  form  which  should  be  given  it  is  better  indicated  by  the 
drawing,  Figs.  173  and  177,  than  a  written  description  would  give. 
The  complicated  provision  for  the  contraction  of  the  fissure  found 
in  older  forms  of  instruments  is  entirely  superseded  in  these  by 
making  the  appliance  somewhat  in  the  form  of  two  leaves,  one  to  lie 
on  the  inferior  and  the  other  upon  the  superior  surface  of  the  palate, 
and  joined  together  along  the  median  line.  When  the  fissure  con- 
tracts, the  halves  of  the  divided  uvula  slide  toward  each  other  be- 
tween these  two  leaves.  The  posterior  portion,  marked  A  in  Fig. 
173,  is  made  very  thin  and  delicate  on  all  its  edges,  as  it  occupies 


3 88  MECHANICAL   DENTISTRY. 

the  chamber  of  the  pharynx  and  is  subject  to  constant  muscular 
movement. 

The  sides  are  rolled  slightly  upward,  while  the  posterior  end  is 
curved  downward.  The  inferior  portion,  marked  D  D,  in  Fig.  173, 
should  reach  only  to  the  base  of  the  uvula,  and  bridge  directly 
across  the  chasm  at  this  point,  and  no  effort  to  imitate  the  uvula 
should  be  made.  The  extreme  posterior  end  should  not  reach  the 
posterior  wall  of  the  pharynx  when  all  the  muscles  are  relaxed  by 
54  of  an  inch,  although  subsequent  use  must  determine  whether 
this  space  be  increased  or  diminished,  thus  leaving  abundant  room 
for  respiration  and  the  passage  of  nasal  sounds.  In  cases  where  it 
is  desirable  to  make  the  instrument  independent  of  the  teeth,  so 
far  as  possible,  in  its  support,  the  anterior  part,  which  occupies  the 
apex  of  the  fissure  in  the  hard  palate  may  lap  over  on  to  the  floor 
of  one  or  both  nares.  Such  a  projection  is  seen  in  Fig.  173, 
marked  B,  and  a  like  process  is  seen  in  Fig.  177,  but  not  lettered. 
Were  it  not  for  this  process  in  this  case,  the  palate  would  drop  out 
of  the  fissure  into  the  mouth,  the  single  clasp  at  the  extreme  an- 
terior end  not  being  sufficient  to  keep  the  whole  appliance  in  place 
throughout  its  entire  length.  Caution  must  be  exercised  that  this 
projection  entering  the  nares  be  not  too  large,,  or  it  will  obstruct 
the  passage  and  give  a  disagreeable  nasal  tone  to  the  voice. 

All  these  described  peculiarities  must  be  provided  for  in  the 
gutta-percha  model,  which,  after  having  been  carefully  formed  to 
the  cast,  may  be  tried  in  the  mouth  to  ascertain  its  length  or 
necessary  variations.  When  its  ultimate  form  has  been  decided 
upon,  provision  must  be  made  to  duplicate  it  in  soft  rubber. 

A  parallel  process,  and  one  which  will  be  a  familiar  illustration, 
is  used  when  a  set  of  teeth  is  made  on  vulcanite  base.  A  model  or 
pattern  form  is  made  of  gutta-percha,  bearing  the  teeth,  and  in  all 
its  prominent  characteristics  is  shaped  as  the  completed  denture 
is  desired,  the  rubber  duplicate  being  vulcanized  in  a  plaster  mold. 
In  like  manner  the  rubber  duplicate  of  the  palate,  as  before  de- 
scribed, may  be  made  in  a  plaster  mold. 

If  plaster  is  used  it  must  be  worked  with  much  care,  so  that  the 
surface  shall  be  free  from  air-bubbles,  or  the  rubber  palate  will  be 
covered  with  excrescences  that  cannot  be  readily  removed.  By 
covering  the   surface  of   the  mold   with   collodion   or  liquid   silex, 


ARTIFICIAL    TREATMENT    OF    PALATAL    DEFECTS. 


389 


it  will  be  much  improved.  But  ordinarily  plaster  molds  will  be 
found  too  troublesome  for  general  use.  They  may  be  put  to  a 
most  excellent  use,  however,  by  using  one  to  make  a  duplicate  of 
the  gutta-percha  in  hard  rubber. 

This  is  not  necessary  with  those  who  have  had  much  experience, 
but  with  beginners  it  will  be  difficult  to  work  up  the  gutta-percha 
as  nicely  as  may  be  desired ;  a  duplicate  of  vulcanite  will  enable 
the  operator  to  make  a  more  artistic  model  of  the  palate,  and  one 
which  can  be  handled  with  greater  freedom. 

As  in  the  course  of  a  lifetime  a  considerable  number  of  elastic 
palates  will  be  required,  the  mold  which  produces  them  should  be 
made  of  some  durable  material.  The  type-metal  of  commerce  is 
admirably  adapted  to  this  use.  The  most  complete  mold  is  one- 
made  of  four  pieces,  which  will  produce  a  palate  of  one  continuous, 

Fig.  175. 


piece.  Such  a  mold  requires  very  nice  mechanical  skill  in  fitting 
all  the  parts  accurately,  and  unless  the  operator  has  had  experience 
in  such  a  direction,  it  is  better  to  simplify  the  matter.  By  making 
the  palate  in  two  pieces,  to  be  joined  after  vulcanizing,  the  mold 
may  be  made  in  two  pieces,  and  with  very  little  trouble. 

Fig.  175  shows  a  palate  divided. 

Fig.  176  shows  the  mold  or  flask  in  which  it  is  vulcanized.  These 
flasks  were  made  expressly  for  this  purpose,  but  they  are  not  so 
unlike  the  flasks  in  common  use  in  dentists'  laboratories  that  the 
latter  will  not  answer.  The  common  flask  is  simply  unnecessarily 
thick  or  deep. 

The  mold  is  really  produced  in  the  following  manner:  Imbed 
the  two  pieces  of  the  palate  in  plaster,  in  one-half  of  the  flask; 
when  the  plaster  is  set  and  trimmed  into  form,  duplicate  it  in  type- 
metal  by  removing  the  palate,  varnishing  the  surface,  molding  in 


39o 


MECHANICAL   DENTISTRY. 


sand,  and  casting.  In  making  the  sand  mold,  take  a  ring  of  sheet- 
iron  of  the  same  diameter  as  the  flask  and  three  or  four  inches 
high;  slip  it  over  the  flask  and  pack  full  of  sand.  Separate  them, 
remove  the  plaster,  return  the  flask  to  the  sand  mold,  and  fill  with 
the  melted  metal  through  a  hole  made  in  the  side  or  bottom  of  the 

Fig.  176. 


flask.      With   one-half   thus   made,    substantially   the   same   process 
will  produce  the  counterpart. 

Fig.  177  shows  the  palate  complete,  with  its  attachment  to  the 
teeth.  The  palate  is  secured  to  the  plate  by  a  pin  of  gold  passing 
through  a  hole  in  the  palate  of  the  same  size;  the  head  on  the  pin, 

Fig.  177. 


being  larger  than  the  hole,  is  forced  through,  and  thus  the  two 
halves  of  the  palate  are  bound  together  and  joined  to  the  plate. 

Fig.  178  shows  a  mold  in  four  pieces.  The  blocks,  C  C,  are 
accurately  adapted  to  the  body  of  the  mold,  marked  A,  and  are 
prevented  from  coming  improperly  in  contact  with  each  other  by 
the  flanges,  D  D,  which  overlap  the  rest  upon  the  sides  of  the 


ARTIFICIAL   TREATMENT    OF    PALATAL   DEFECTS. 


391 


main  piece.     B  shows  the  top  of  the  mold,  and  the  groove,   E, 
provides  for  the  surplus  rubber  in  packing-. 

Such  a  mold  makes  the  most  perfect  appliance  that  can  be  pro- 
duced.     The    palate    is    one    homogeneous    and    inseparable    piece. 

Fig.  178. 


The  cut  will  sufficiently  indicate  the  forms  of  the  several  parts. 
Each  of  these  pieces  is  first  made  in  plaster  of  exactly  the  form  of 
which  the  type-metal  is  desired.  They  are  then  molded  in  sand 
and  the  type-metal  cast  as  in  making  an  ordinary  die  for  swaging. 

Fig.  179. 


When  in  use,  a  clamp  similar  to  Fig.  179  is  placed  around  the  mold 
to  keep  the  several  parts  firm  in  their  position. 

The  packing  of  the  mold  with  rubber  will  be  done  in  the  same 
manner  as  when  hard  rubber  is  used  for  teeth  bases,  with  which 


392 


MECHANICAL   DENTISTRY. 


process  it  is  assumed  that  the  operator  is  familiar.  By  washing 
the  surface  of  the  mold  with  a  thick  solution  of  soap  previous  to 
packing,  the  palate  will  be  more  easily  removed  after  vulcanizing. 

The  rubber  used  for  this  purpose  must  be  a  more  elastic  com- 
pound than  that  used  as  a  base  for  teeth.  The  composition  used 
for  the  elastic  fabrics  of  commerce  will  answer  if  made  of  selected 
materials. 

Suersen's  Obturator. — Dr.  Wilhelm  Suersen,  of  Berlin,  intro- 
duced an  obturator,  the  principle  of  which  has  seemed  to  many 
the  best  for  obtaining  correct  articulation.  In  describing  it  in 
The  American  Journal  of  Dental  Science,  he  says : 

"  In  order  to  be  able  to  pronounce  all  letters  distinctly,  it  is 
accordingly  necessary  besides  other  conditions,  which  are  far  away 
from  our  present  subject,  to  separate  the  cavity  of  the  mouth 
from  the  cavity  of  the  nose  by  means  of  muscular  motion.  That 
separation  is,  under  normal  conditions,  effected,  on  the  one  hand, 
by  the  velum  palati,  which  strains  itself  (consequently  by  the  leva- 
tor and  tensor  palati)  ;  but,  on  the  other  hand,  also,  by  a  muscle 
which,  to  my  knowledge,  has,  in  connection  with  these  operations, 
not  yet  received  a  sufficient  amount  of  attention — I  mean  the  con- 
strictor pharyngeus  superior.  This  muscle  contracts  itself  during 
the  utterance  of  every  letter  pronounced  without  a  nasal  sound, 
just  as  the  levator  palati  does.  The  constrictor  muscle  contracts 
the  cavum  pharyngopalatinum,  the  pharynx  wall  bulging  out; 
and  it  is  chiefly  on  the  action  of  this  muscle  that  I  base  the  system 
of  my  artificial  palates. 

"  These  palates,  which  in  all  their  parts  are  made  of  hard  caout- 
chouc, consist  of  a  teeth-plate  suitably  attached  to  existing  teeth, 
and  which,  at  the  same  time,  covers  the  fissure  in  the  hard  palate, 
if  such  a  fissure  exists.  Where  the  fissure  commences  in  the  velum, 
that  plates  terminates  in  an  apophysis  broad  enough  for  filling  up 
the  defect.  This  apophysis  is  at  the  same  time  of  such  thick- 
ness as  to  keep  up  a  contact  between  the  high  edges  forming  the 
sides  of  the  apophysis  and  the  two  halves  of  the  velum,  even 
when  the  levator  palati  is  in  activity.  To  bring  about  this  contact 
the  more  surely,  the  high  edges  forming  the  sides  do  not  rise 
straight,  but  obliquely,  toward  the  outside.  The  lower  surface  of 
the  apophysis,  turned  toward  the  mouth,  lies  on  about  an  equal 
level  with  the  velum  if  the  latter  is  raised  by  the  levator  palati.    But 


ARTIFICIAL    TREATMENT    OF    PALATAL   DEFECTS. 


393 


when  the  velum  hangs  loosely  downward,  the  back  part  of  the 
artificial  palate  is  lying  over  it.  This  back  part,  accordingly,  fills 
up  the  cavum  pharyngopalatinum,  and  in  such  a  manner  as  not 
to  impede  the  entrance  of  the  air  into  the  cavity  of  the  nose  when 
the  constrictor  pharyngeus  superior  is  inactive.  Thus  the  patient 
can  without  any  impediment  breathe  through  the  nose.  But  as 
soon  as  the  constrictor  contracts  the  cavum  pharyngopalati  (this 
happens,  as  I  will  repeat  for  the  sake  of  clearness,  in  the  utterance 
of  every  letter  with  the  exception  of  m  and  n),  the  muscle  already 
named  reclines  against  the  vertical  back  surfaces  of  the  obturator. 
By  this  operation  the  air-current  is  prevented  from  entering  the 
cavity  of  the  nose,  and  is  compelled  to  take  its  way  through  the 

Fig.  180. 


mouth,  and  thus  the  utterance  loses  its  nasal  sound.  To  the  ex- 
istence of  those  vertical  surfaces,  and  consequently  to  the  thick- 
ness of  that  part  of  my  palates  which  fills  up  the  fissure  in  the 
soft  palate  and  the  cavum  pharyngopalatinum,  I  must  attach 
special  importance.  But  for  that  thickness  the  levator  palati, 
when  it  rises  upward,  would  not  remain  in  contact  with  the  side 
edges  of  the  obturator,  nor  would  the  constrictor  pharyngeus  be 
able  to  effect  a  sufficient  termination  if  the  portion  of  the  obtura- 
tor nearest  to  it  consisted  only  of  a  thin  plate." 

Fig.  180  represents  the  mouth  without  the  apparatus. 

Fig.  181  shows  the  apparatus  in  position ;  Fig.  182  gives  a  view 
of  the  appliance  out  of  the  mouth. 


394 


MECHANICAL   DENTISTRY. 


Dr.  Henry  Baker,  in  writing  of  this  appliance  in  the  "American 
System  of  Dentistry,"  says  : 

"  The  plate,  a,  and  its  narrow  and  thin  apophysis,  i,  which  ex- 


Fig.  181. 


tends  from  the  boundary,  b,  of  the  hard  palate  to  the  commence- 
ment of  the  defect,  c,  in  the  soft  palate,  serve  also  as  supporters  to 
the  real  thick  obturator,  d.    The  latter  lies  in  the  pharyngopalatine 


Fig.   182. 


hollow,  so  that  the  lower  surface  of  the  obturator  turned  toward 
the  mouth,  is  about  on  the  same  level  as  the  rest  of  the  velum 
palati,  e.     Against  the  vertical  side,  /,  and  back  edges,  g,  of  the 


ARTIFICIAL   TREATMENT    OF    PALATAL   DEFECTS.  395 

obturator  the  walls  of  the  pharynx  lean  if  the  latter  is  contracted 
by  a  contraction  of  the  superior  constrictor  of  the  pharynx.  But 
if  the  muscle  just  mentioned  is  not  in  activity,  the  obturator  does 
not  touch  the  pharyngeal  wall.  The  contraction  of  the  constrictor 
superior,  therefore,  closes  the  valve  formed,  with  the  help  of  the 
obturator,  between  the  cavity  of  the  mouth  and  that  of  the  nasal 
bone,  while  any  relaxation  of  the  above-mentioned  muscle  imme- 
diately reopens  that  valve.  The  thickness  of  the  obturator  begins 
where  the  fissure  in  the  soft  palate  commences.  With  the  high 
side  edges  of  the  fore  part  of  the  thick  obturator,  which  edges 
ascend,  not  straight  but  obliquely,  toward  the  outside,  the  side 
halves  of  the  fissured  velum  palati,  e,  are  in  constant  contact,  even 
when  the  latter  are  raised  by  the  action  of  the  muscular  levator 
palati.  The  proportions  of  the  back  part,  which,  in  the  same 
manner  as  in  the  case  of  an  acquired  defect,  fill  up  the  cavum 
pharyngopalati,  k  k,  are  the  two  halves  of  the  fissured  uvula." 

Dr.  Suersen  admits  the  importance  of  the  part  taken  by  the 
levator  palati  muscles  in  the  formation  of  articulate  speech ;  yet  he 
makes  no  provision  for  utilizing  them  as  such,  and  provides  only 
for  the  contact  of  the  superior  constrictor  muscle  with  the  distal 
surface  of  the  appliance  to  shut  off  the  nasal  passage.  For  the 
patient  afflicted  with  congenital  cleft,  to  acquire  perfect  articulation 
with  such  an  appliance,  even  if  it  be  possible,  years  of  application 
and  training  of  this  muscle  would  be  necessary ;  and  a  little 
reflection  will  show  that  this  muscle,  besides  performing  its  own 
functions,  must  be  trained  to  fulfil  those  of  the  velum  palati, 
levator  palati,  and  tensor  palati.  But  in  an  accidental  lesion  this 
may  be  all  that  is  necessary,  as  the  patient  having  previously 
learned  to  articulate  distinctly,  and  having  this  deformity  come 
upon  him  afterward,  the  superior  constrictor  muscle  would  no 
doubt  be  sufficiently  developed  to  perform  that  function.  Sir 
William  Ferguson,  in  his  report  of  a  dissection  made  by  him  of  a 
cleft  palate,  in  1844,  states  distinctly  that  the  constrictor  was  very 
full,  and  he  also  claimed  for  that  muscle  very  decided  forward  ac- 
tion in  deglutition. 

Dr.  Kingsley,  in  speaking  of  Suersen's  appliance,  says :  "  First, 
that  of  all  obturators  this  is  the  best  form  for  congenital  fissure, 
but  while  the  wearer  is  enabled  to  articulate  with  such  an  instru- 
ment, it  is  only  after  he  has  learned  articulation  with  another  ap- 


396 


MECHANICAL   DENTISTRY. 


paratus.  Second,  that  a  soft,  elastic,  artificial  velum  is  much  better 
adapted  to  the  acquirement  of  articulation  than  any  unyielding, 
non-elastic  substance,  but  when  acquired  an  obturator  may  be  sub- 
stituted. Third,  that  in  very  rare  cases  articulation  may  be  acquired 
with  an  obturator  only,  but  it  is  the  extra  activity  of  the  pharyngeal 
muscles,  while  with  the  elastic  velum  the  levators  of  the  palate 
contribute  largely." 

Baker's  Velum. — Dr.  Henry  Baker  describes  his  appliance  as 
follows :  "  Numerous  experiments  to  provide  an  artificial  appliance 


Fig.  183. 


The  cleft,  extending  a  little  beyond  the  soft  into  the  hard  palate. 

with  hard  rubber,  utilizing  the  levator  muscles  to  control  the 
movement  of  the  appliance,  and  with  which  articulation  could  be 
learned  as  well  as  with  the  perishable  soft-rubber  velum,  resulted  in 
my  adoption  of  the  following  device  in  cases  where  the  cleft  extends 
a  little  beyond  the  soft  into  the  hard  palate,  as  shown  in  Fig.  183. 
The  appliance  consists  of  a  gold  or  hard-rubber  plate  (A,  Fig.  184), 
covering  the  roof  of  the  mouth  down  to  the  junction  of  the  hard 
and  soft  palates.  From  this  point  the  movable  portion,  F,  extends 
back  and  downward,  restoring  symmetry  of  the  palatal  surface  by 


ARTIFICIAL    TREATMENT    OF    PALATAL   DEFECTS. 


397 


bridging  across  and  lying  upon  the  muscles  of  each  side.     C  E  is 
a  spring  controlling  the  upward  movement  of  F.     The  distal  sur- 


FlG. 


face,   G,  or  that  portion   coming  in  contact  with  the  pharyngeal 
wall,  is  quite  broad,  and  so  constructed  as  to  articulate  perfectly 


Fig.  185. 


■with  this  surface,  while  the  constrictor  muscle  contracts  and  closes 
around  it  on  a  semicircle."  This  is  the  Suersen  principle,  and  the 
main  ideas  are  taken  from  that  appliance. 


39§ 


MECHANICAL   DENTISTRY, 


The  velum  is  of  polished  hard   rubber,   gold,  or  platinum,   and 
much  resembles  a  chestnut  in  form. 

It  is  attached  to  the  plate  with  a  hinge-joint,  B  B,  thus  giving 


Fig.   i 


free  movement  at  the  junction  of  the  hard  and  soft  palates.  At  the 
junction  of  the  hard  and  soft  palates  there  is  a  stop,  which  prevents 
any  downward  pressure  upon  the  muscles  when  in  a  relaxed  con- 
dition. 

Fig.  187. 


The   muscles   relaxed,    the   appliance    descended,    thus   giving   a   free   passage    for 
nasal   sounds  and  respiration. 

Fig.  185  shows  the  appliance  in  position,  the  dotted  lines  show- 
ing the  part  of  the  appliance  resting  on  the  muscles. 

The  main  advantages  of  this  appliance  are  that  it  is  made  of  a 
durable  material,  is  easily  constructed,  and  that  articulation  can  be 


ARTIFICIAL    TREATMENT   OF    PALATAL   DEFECTS.  399 

learned  with  it  more  readily  than  with  any  other  appliance.  In 
addition,  it  is  so  easily  movable  as  to  be  acted  upon  by,  and  be 
under  perfect  control  of  the  muscles  by  which  it  is  surrounded. 
In  studying  the  mechanism  of  speech,  we  learn  that  more  than 
three-fourths  of  the  sounds  of  articulate  language  depend  upon  the 
integrity  of  the  soft  palate  for  their  perfect  enunciation.  This  being 
the  fact,  articulation  with  a  rigid  obturator  must  be  extremely 
difficult  to  acquire.  If  three-fourths  of  the  sounds  depend  on  the 
free  movement  of  the  natural  palate,  it  seems  a  sufficient  reason  why 
provision  should  be  made  for  the  same  movement  in  an  artificial 
one. 

Dr.  Kingsley  says  that  with  a  yielding  appliance  the  levators  of 
the  palate  contribute  largely  to  correct  speech.  The  surrounding 
muscles  have  control  over  the  appliance  here  described  in  the 
following  way :  The  artificial  velum  bridges  across  the  opening 
and  lies  upon  the  muscles  of  either  side.  (See  Fig.  185,  D  D.) 
With  all  sounds  requiring  the  closure  of  the  nasal  passage  it  is 
thrown  up  by  the  levator  muscles,  as  shown  at  D  in  the  sectional 
Fig.  186,  there  being  no  resistance.  The  thickness  of  the  velum 
brings  its  posterior  surface  in  close  apposition  with  the  superior 
constrictor  muscle,  F,  affording  in  the  pronunciation  of  the  gutturals 
a  firmer  resistance  to  the  pressure  of  the  tongue,  G,  than  can  be 
obtained  with  a  thin  obturator.  By  the  presence  of  the  hinge,  B, 
the  above  movements  are  rendered  so  free  and  facile  that  there  is 
no  tendency  to  displacement  of  the  plate,  such  as  occurs  with  a 
rigid  appliance.  If  a  nasal  sound  immediately  follows  a  guttural, 
the  descent  of  the  velum  is  rendered  certain  by  its  own  weight,  even 
if  not  aided  by  the  spring. 


CHAPTER    XXVIII. 

APPLIANCES    FOR    THE    CORRECTION    OF    FRACTURED 

MAXILLA. 

(Interdental  Splints.) 

Dentists  are  peculiarly  fitted  to  overcome  the  mechanical  diffi- 
culties in  the  treatment  of  fractures  of  the  maxillae ;  while  the 
general  surgeon,  whose  services  are  usually  first  sought,  encounters 
many  annoyances,  and  seldom  secures  a  correct  adaptation  and 
retention  of  the  fragments  in  their  normal  position.  In  fact,  all 
of  the  approved  appliances  and  methods  have  emanated  from 
dentists. 

Fractures  of  the  jaw  are  unmistakable,  the  prominent  symptoms 
being  pain,  swelling,  drooling,  mobility  of  the  fragments,  crepitus, 
and  displacement  of  the  teeth.  If  there  is  any  doubt  as  to  the 
location  of  the  fracture  of  the  lower  jaw,  the  operator  should  be 
seated  in  front  of  the  patient,  and  gently  but  firmly  grasp  the  bone 
on  either  side,  allowing  the  forefinger  to  extend  into  the  mouth  and 
rest  upon  the  teeth,  when  the  false  point  of  motion  or  crepitus  will 
be  readily  recognized. 

The  Division  of  Fractures. — Fractures  are  divided  into  simple, 
compound,  and  comminuted.  Simple,  when  the  bone  only  is  broken 
without  piercing  the  integuments ;  compound,  when  the  fracture  is 
accompanied  by  laceration  of  the  tissues  through  to  the  surface,  so 
as  to  establish  communication  with  the  air;  comminuted,  when  the 
bone  is  broken  or  crushed  into  several  pieces.  If  the  body  of  the 
bone  is  involved,  fractures  of  the  lower  jaw  are  usually  compound 
in  the  direction  of  the  mouth ;  but  when  the  ramus,  condyle,  or 
coronoid  process  are  fractured  this  is  not  the  case  (on  account  of 
their  being  so  deeply  seated)  unless  the  wound  is  caused  by  a  gun- 
shot or  missile.  Several  cases  of  fractured  maxillae  have  been  sent 
to  the  writer  for  treatment,  at  the  clinics  of  the  Pennsylvania  Col- 
lege of  Dental  Surgery.  These  operations  have  been  carried  out 
according  to  the  principles  herein  described,  and  with  entirely  satis- 
factory results. 

400 


APPLIANCES  FOR  THE   CORRECTION   OF  FRACTURED   MAXILLAE.   40I 

Securing  the  Impression. — The  fundamental  principles  of  tak- 
ing the  impressions  of  both  jaws  and  reconstructing  the  model  of 
the  fractured  jaw  by  articulating  the  teeth  to  the  cast  of  the 
unbroken  jaw,  and  upon  this  making  the  appliance,  or  splint,  were 
inculcated  by  Drs.  Gunning  and  Bean. 

The  impression  of  both  jaws  should  be  taken,  either  in  wax  or 
modeling  compound,  using  as  small  a  quantity  as  will  insure  a 
good  impression  of  the  teeth  and  gums.  That  of  the  uninjured 
jaw  should  be  taken  first,  thus  gaining  the  confidence  of  the  patient, 
and  deferring  the  most  painful  operation  until  the  last. 

As  it  is  impossible  to  keep  the  fragments  of  a  fractured  inferior 
jaw  in  perfect  apposition  while  taking  an  impression,  no  attempt 
should  be  made  to  entirely  reduce  the  fracture  at  this  time.    The  sec- 


FlG.    I 


tions,  however,  should  be  brought  as  nearly  to  position  as  possible 
without  causing  much  pain  to  the  patient. 

An  assistant  should  stand  behind  the  patient  and  support  the 
broken  jaw,  keeping  it  steady  while  the  impression  is  being  taken. 
This  is  more  important,  however,  when  the  fracture  is  double. 

The  impression  material  being  ready,  it  should  be  introduced 
into  the  mouth  and  carefully  brought  to  position,  and  much  care 
should  be  exercised  to  prevent  the  pieces  of  bone  and  loosened 
teeth  from  moving  when  this  material  is  being  molded  about  their 
necks. 

Preparing  the  Models. — After  the  impression  has  been  secured, 
mix  plaster  and  pour  cast  in  the  usual  manner.  Figs.  188  and  189 
represent  casts  showing  double  fractures. 

The  casts  or  models  of  both  jaws  being  obtained,  they  should 
be  carefully  articulated.  This  is  done  by  cutting,  with  a  small  saw, 
26 


402 


MECHANICAL   DENTISTRY, 


the  lower  cast  at  the  point,  or  points,  of  fracture,  and  rearranging 
the  sections  thus  made  so  as  to  bring  the  teeth  of  the  two  models 
into  correct  articulation.     This  is  represented  in  Fig.  189. 

The  pieces  should  then  be  secured  in  this  position  with  plaster 
and  the  two  models  placed  in  an  articulator. 

Forming  the  Splint  in  Wax. — Any  interdental  dovetail  spaces 
should  be  filled  with  soft  plaster,  so  that  the  splint  when  finished 
can  be  readily  adjusted  and  removed. 

The  articulator  should  now  be  arranged  (by  the  set  screw  in  the 
back)  so  as  to  open  the  bite  about  y2  of  an  inch.  Carefully  cover 
teeth'  and  gums  of  both  casts  with  No.  60  tin-foil.  Over  this 
covering  of  tin-foil  build  up  the  splint  in  wax.     This  is  best  done 

Fig.  189. 


as  directed  by  the  late  Dr.  Alonzo  Beak*  First,  place  two  layers 
of  thin  base-plate  wax  over  the  teeth  of  both  models,  allowing  it 
to  extend  just  beyond  the  necks  of  the  teeth  upon  the  gums,  but 
not  quite  to  the  edge  of  the  tin-foil.  Then  make  a  strip  of  wax 
about  yV  °f  an  mcn  thick  and  wide  enough  to  fit  between  the 
pieces  of  wax  on  the  models,  and  long  enough  to  extend  as  far 
back  as  they  do,  joining  the  three  pieces  together  with  melted  wax. 
Pass  a  hot  spatula  all  around  the  edge  of  the  wax,  where  it  joins 
the  tin-foil,  to  make  a  perfect  joint.  The  object  of  the  tin-foil  is  to 
make  the  rubber  smooth,  and  to  have  the  splint,  when  finished,  a 
trifle  larger  than  the  natural  teeth,  so  that  it  will  pass  into  position 
without  binding  at  any  point. 


*  "  American  System  of  Dentistry,"  Vol.  ii. 


APPLIANCES   FOR  THE  CORRECTION   OF   FRACTURED    MAXILLJE.   403 

Flasking. — The  wax  splint  and  tin-foil  covering,  now  being  one 
piece,  should  be  removed  from  the  models  and  the  models  care- 
fully taken  from  the  articulator.  Trimming  their  bases  and  sides  is 
necessary,  so  that  when  the  splint  is  in  position  on  them  the  whole 
will  fit  in  the  vulcanizing  flask.  The  lower  model,  with  the  splint 
upon  it,  should  be  flasked  first  and  the  investment  allowed  to  ex- 
tend half  way  up  the  splint.  Trim,  varnish,  and  oil.  Place  the 
upper  model  in  position  in  the  splint  and  finish  flasking.  By  allow- 
ing the  tin-foil  to  extend  beyond  the  wax  (as  at  T,  Fig.  190)  the 
investment  holds  it  in  position  when  the  wax  is  removed.  Fig. 
190  gives  a  sectional  view  of  the  flask  with  the  splint  invested.  F 
represents  the  flask ;  M,  the  models ;  P,  plaster  investment ;  T,  tin- 


Fig.  190. 


foil  coverings  of  the  teeth  extending  beyond  the  wax  splint;  W, 
wax  model  of  splint.  Before  opening  the  flask  place  it  in  hot  water 
to  soften  the  wax.  Separate  the  sections  carefully.  Wash  the  wax 
out  by  pouring  boiling  water  upon  it,  instruments  not  being  used, 
as  they  are  liable  to  injure  the  tin-foil. 

Packing  and  Vulcanizing. — Liberal  outlets  for  the  rubber 
should  be  made  in  both  sections.  Cut  the  rubber  into  thin  strips 
and  soften  over  boiling  water.  It  is  also  advisable  to  cut  up  a  piece 
of  previously  vulcanized  rubber,  small  pieces  of  which  may  be  packed 
in  between  the  other  rubber  at  the  thickest  points,  making  it  less 
liable  to  become  porous  in  vulcanizing.  Pack  each  section  care- 
fully and  thoroughly  a  little  more  than  full.  Place  the  sections 
together,  boil,  and  close  them  in  the  usual  way.     In  vulcanizing 


404 


MECHANICAL   DENTISTRY, 


allow  the  mercury  one  hour  to  rise  to  3200  F.     When  this  point  is 
reached  the  temperature  should  be  kept  uniform  for  one  hour  or 

more. 

Fig.  191. 


Finishing. — When  the  flask  is  taken  from  the  vulcanizer  and 
has  become  cold,  carefully  remove  the  plaster  and  tin-foil  from  the 
rubber.  In  trimming-,  the  rubber  should  be  cut  away  nearly  to  the 
necks  of  the  teeth  and  the  edges  all  nicely  rounded.     The  opening 

Fig.  192. 


made  in  the  splint  for  feeding  purposes  should  be  in  front,  if  pos- 
sible, and  large  enough  to  allow  for  the  free  passage  of  a  feeding 
tube,  and  should  have  the  edges  well  rounded.  The  splint  should 
now  be  immersed  in  dilute  muriatic  acid  to  dissolve  the  tin,  after 


APPLIANCES  FOR  THE   CORRECTION  OF  FRACTURED   MAXILLAE.   405 

which  it  should  be  carefully  finished  and  polished.  Fig.  191  repre- 
sents the  completed  splint.  It  is  often  advisable  to  make  openings 
through  the  top  or  side  of  the  splint  against  each  tooth  adjoining 
the  fracture,  so  that  it  can  be  determined  when  the  fractures  are  in 
place.     This  plan  is  represented  in  Fig.   192. 

Securing  Splint  in  the  Mouth. — The  splint  is  now  ready  to  be 
adjusted  in  the  mouth,  and  if  the  foregoing  instructions  have  been 
closely  followed  the  teeth  of  the  superior  jaw  will  readily  slip  into 
place.  After  so  placing  it,  carefully  manipulate  the  lower  jaw, 
reducing  the  fracture  and  bringing  the  teeth  to  position  in  the  splint. 
The  jaw  should  then  be  firmly  secured  by  external  bandages. 

The  Kingsley  Splint. — A  splint  devised  by  Dr.   Norman  W. 


Kingsley  consists  of  a  vulcanite  covering  to  the  lower  teeth,  having 
two  steel  wires  attached  extending  out  of  the  corners  of  the  mouth 
and  then  backward  along  the  cheek  on  a  line  with  the  teeth.  It 
is  held  in  position  by  having  the  wires  bound  to  a  sub-metal  splint 
of  padded  wood.  The  upper  teeth  must  articulate  with  the  upper 
surface  of  the  rubber,  so  that  the  patient  can  use  it  for  mastica- 
tion. Take  upper  and  lower  impressions ;  pour  models  and  articulate 
them,  as  before  described,  and  place  them  in  an  articulator.  Upon 
the  lower  model  carefully  press  a  piece  of  wax  about  one  line  in 
thickness  over  the  teeth,  allowing  it  to  encroach  a  little  upon  the 
gums.  Close  the  articulator  to  make  the  imprints  of  the  upper 
teeth  in  the  wax.  The  best  method  to  make  the  arms  is  to  use  a 
couple  of  old  dental  excavators.     Flatten  the  ends  which  are  to  be 


406 


MECHANICAL    DENTISTRY. 


imbedded  and  curve  them  carefully,  so  that  they  will  pass  out  of  the 
mouth  and  extend  backward  without  pressing  hard  on  the  corners 
of  the  mouth,  and  terminate  near  the  angle  of  the  jaw.  The  flat- 
tened ends  should  be  made  quite  broad  and  be  thoroughly  imbedded 

Fig.  194. 


in  the  splint,  as  much  strain  comes  upon  them.     Fig.  193  represents 
this  form  of  splint. 

The  following  cases,  taken  from  the  practice  of  Dr.  Kasson  C. 
Gibson,  of  New  York,  are  of  especial  interest  in  this  connection. 
Fig.  194  represents  a  fracture  at  the  symphysis;  Figs.  195  and  196 
the  displaced  fragments  sawed  from  the  casts. 


Fig.  195. 


Fig.  196. 


The  occluding  or  grinding  surfaces  of  antagonistic  teeth  are 
unmistakable,  and  tbere  is  no  excuse  for  making  an  error  in  reset- 
ting the  plaster  model.  Should  any  discrepancy  occur,  it  will  be 
fatal  to  the  success  of  the  appliance.     In  all  cases  where  there  are 


APPLIANCES   FOR  THE  CORRECTION   OF  FRACTURED   MAXILLAE.  407 

teeth  which  occluded  with  those  of  the  opposite  jaw  (previous  to 
the  fracture)  a  mistake  is  impossible,  if  care  be  exercised. 

Fig.  197  shows  the  plaster  fragments  placed  in  their  normal  posi- 
tion and  cemented  together,  ready  for  the  articulator. 

If  fractures  where  the  teeth  are  missing,  take  an  impression  of 
the  alveolar  ridge  in  the  same  manner  as  for  artificial  teeth,  and 
there  will  be  no  difficulty  in  correcting  the  model.  The  splint  should 
be  molded  with  wax  on  the  reconstructed  plaster  cast,  and  must 
embrace  each  fragment  of  the  jaw.  If  to  be  used  for  mastication, 
the  splint  should  cover  all  the  teeth. 

After  modeling  the  splint  in  wax,  and  just  before  removing  the 
cast  for  flashing,  soften  the  wax  with  dry  heat.  (The  grinding 
surface  of  the  teeth  should  have  been  previously  oiled  to  prevent 
their  adhering.)      Then  close  the  articulator,  forcing  the  grinding 

Fig.  197. 


surface  of  the  upper  teeth  into  the  wax,  thus  giving  a  uniform  grind- 
ing surface.  Before  packing  the  rubber,  cover  the  teeth  and  model 
with  two  or  three  thicknesses  of  tin-foil.  There  are  two  reasons  for 
doing  this :  first,  it  makes  the  splint  a  trifle  larger ;  second,  it  gives 
a  clean  surface.  After  vulcanizing,  immerse  the  splint  in  diluted 
muriatic  acid  to  dissolve  the  tin.  Interdental  splints  ought  to  be  so 
adjusted  that  mastication  can  be  performed. 

In  many  fractures  of  the  lower  jaw  it  will  be  impossible  to  hold 
the  fragments  in  the  splint,  in  their  normal  relations,  by  merely 
attaching  them  to  the  splint.  In  these  cases  the  appliance  must  be 
supplemented  by  an  external  metal  compress,  so  attached  to  it  that 
the  jaw  will  be  held  as  in  a  vise.  The  tightening  of  this  compress 
forces  the  fragments  into  the  splint  and  securely  holds  them. 

Fractures  of  the  upper  jaw  require  but  little  treatment  compared 


408  MECHANICAL   DENTISTRY. 

with  those  of  the  lower,  since  the  bones  are  naturally  immovable, 
and  there  is  little  difficulty  in  keeping  the  fragments  in  position. 

The  length  of  time  necessary  for  wearing  an  interdental  splint  is 
variable ;  the  shortest  time,  however,  being  about  three  weeks. 

Brief  histories  of  the  following  cases  are  furnished  as  illustrating 
the  different  methods  and  appliances  used  in  the  treatment. 

Case  i. — Male,  aged  fifty.  Treated  at  Bellevue  Hospital.  Lower 
jaw  fractured  on  the  left  side,  the  line  extending  through  the  body 
between  the  cuspid  and  first  bicuspid.  The  displacement  of  the 
posterior  fragment  was  downward  and  outward.  No  displacement 
of  the  right  side. 

The  splint  used  for  this  patient  was  made  of  vulcanite,  covering 
all  the  teeth,  and  held  in  position  by  first  tying  ligatures  to  the  teeth 
and  afterward  to  the  splint.  The  holes  on  the  grinding  surface  were 
for  two  purposes :  first,  to  ascertain  if  the  teeth  were  in  proper  posi- 
tion ;  second,  to  introduce  the  nozzle  of  the  syringe  for  cleansing. 
After  reducing  the  fracture  and  adjusting  the  splint,  the  patient  was 
enabled  to  masticate  without  any  difficulty.  The  splint  was  worn 
about  four  weeks,  and  on  its  removal  occlusion  of  the  teeth  was 
found  to  be  correct. 

Case  2. — Male,  aged  thirty-five.  Treated  in  Bellevue  Hospital. 
Lower  jaw  fractured  in  two  places;  on  the  right  side  between  the 
lateral  incisor  and  cuspid,  and  on  the  left  of  the  symphysis,  between 
the  central  and  lateral  incisors.  Two  incisors  on  the  right  side  and 
one  on  the  left  side  had  been  knocked  out  at  the  time  of  the  injury. 
The  anterior  fragment  was  forced  back  and  downward  under  the 
tongue;  the  left  side  of  jaw  displaced  downward  and  inward.  (See 
Fig.  198.) 

A  splint  similar  to  the  one  just  described  was  applied,  except  that 
after  inserting  the  splint  and  reducing  the  fracture  a  chin  piece  of 
gutta-percha  (the  impression  material  now  used  by  dentists  is  much 
better),  padded  with  cotton,  held  in  position  with  a  four-tailed  band- 
age, was  added.  Nourishment  was  taken  through  a  space  left  in 
the  splint.      (See  Fig.   199.) 

After  a  few  days  it  became  necessary  to  remove  the  chin  piece, 
as  the  patient  complained  of  soreness  and  pain.  It  was  then  dis- 
covered that  an  abscess  had  formed  on  the  left  side  of  the  symphy- 
sis. This,  on  being  opened  and  probed,  was  found  to  contain  a 
small  piece  of  bone,  which  was  removed.     The  parts  were  cleansed 


APPLIANCES  FOR  THE  CORRECTION  OF  FRACTURED   MAXILLAE. 


409 


with  a  solution  of  carbolic  acid  and  glycerin,  the  cotton  padding 
renewed,  and  the  chin  piece  reapplied.  This  was  frequently  re- 
moved for  renewing  the  cotton  and  for  treatment  of  the  abscess, 


Fig. 


which  healed  in  a  few  days.  About  this  time  a  second  abscess 
formed  under  the  splint,  near  the  symphysis.  This,  on  being 
opened,  contained  a  piece  of  alveolar  process,  which  was  removed. 

Fig.   199. 


A.  Space  through  which  nourishment  was  taken.  B,  B.  Holes  and  slots  for  tying 
the  ligatures  to  the  splint,  these  having  been  previously  tied  around  the  teeth. 
These  holes  were  also  used  for  introducing  the  nozzle  of  a  syringe  for  clean- 
sing.    C,    C.   Ligatures.     D.  Ligature   tied. 

Later  several  other  pieces  of  alveolar  process  presented  themselves 
at  or  near  this  opening,  and  were  removed.  At  the  end  of  three 
weeks  the  union  of  the  fragments  was  sufficiently  firm  to  permit 


410  MECHANICAL   DENTISTRY. 

of  the  removal  of  the  chin  piece,  allowing  the  use  of  the  jaw  for 
mastication.  The  bandage,  however,  was  retained,  except  when 
nourishment  was  being  taken.  The  splint  was  removed  after  being 
worn  about  six  weeks,  when  occlusion  of  the  teeth  was  found  to  be 
correct. 

Case  j. — The  patient,  a  miner,  aged  twenty-seven.  Three  days 
before  admission  to  the  hospital,  May  2,  1872,  he  was  injured  by  a 
splinter  of  wood  from  an  explosion  of  nitroglycerin.  Examination 
revealed  a  compound  comminuted  fracture  of  right  half  of  inferior 
maxilla.  There  were  three  points  of  fracture :  first,  between  the 
left  lateral  incisor  and  the  cuspid ;  second,  between  the  bicuspids ; 
third,  at  or  near  the  angle  of  the  jaw ;  considerable  displacement 
of  all  the  fragments. 

The  anterior  fragment,  containing  three  incisors,  the  cuspid,  and 
first  bicuspid,  was  depressed  y2  of  an  inch  and  displaced  backward. 
The  middle  fragment,  including  the  second  bicuspid  and  three 
molars,  was  carried  up  nearly  to  the  median  line  and  slightly  back- 
ward.    The  posterior  fragment  was  slightly  elevated. 

A  splinter  of  wood  about  3^2  of  an  inch  long  had  been  extracted 
from  an  external  wound  which  extended  inward  from  the  symphy- 
sis for  iy2  inches  along  the  line  of  the  jaw.  A  clot  of  blood  occu- 
pied the  left  side  of  the  floor  of  the  mouth ;  there  was  also  consider- 
able swelling  about  the  face.  The  patient  swallowed  with  difficulty, 
fluids  escaping  through  the  nose ;  articulation  very  indistinct. 

May  3.  Patient  partook  of  milk  through  a  glass  tube  with  less  dis- 
comfort than  the  day  before. 

May  4.  Patient  still  unable  to  swallow  with  ease,  although  the 
swelling  had  greatly  subsided.  An  attempt  was  made  to  introduce 
the  stomach-pump,  but  patient  would  not  submit.  In  the  afternoon 
Prof.  Stephen  Smith  saw  him  and  advised  wiring  the  anterior  frag- 
ments in  order  to  draw  and  retain  the  tongue  forward.  This  was 
accomplished,  though  not  without  some  difficulty,  and  the  patient 
drank  two  glasses  of  milk.  About  two  hours  later  the  wire  broke, 
but  the  patient  was  able  to  swallow  as  well  as  before,  although  com- 
plaining of  pain  during  the  act. 

May  5.  Patient  took  three  cups  of  coffee.  Fragments  again 
wired  in  position. 

May  6.  Patienl  swallowed  all  the  food  he  wished.  Wire  failed  to 
hold  fragments  in  place. 


APPLIANCES   FOR  TPIE   CORRECTION  OF   FRACTURED   MAXILLA.   4H 

May  7.  Swelling  had  almost  disappeared.  Odor  from  the  mouth 
was  very  offensive. 

May  9.  Large  fragment  of  the  jaw,  containing  one  bicuspid  and 
two  molars,  became  detached  during  the  night,  and  the  third  molar 
also  came  away  (Fig.  200).    Treatment  up  to  this  time  consisted  of 

Fig.  200.  Fig.  201. 


Model  showing  displacement. 

•disinfecting  the  mouth  with  a  solution  of  carbolic  acid  and  glycerin. 
The  wound  was  also  dressed  with  the  same,  and  the  jaw  supported 
with  a  four-tailed  bandage. 

May  15.  Impressions  were  taken  in  plaster-of- Paris  preparatory 
"to  making  an  interdental  splint  (Fig.  201).     This  was  constructed 

Fig.  202. 


•similar  to  those  already  described,  with  the  addition  of  two  steel 
wires  (old  excavators)  vulcanized  in  the  splint  and  curved  upward 
as  they  emerged  from  the  corners  of  the  mouth,  thus  avoiding 
pressure  on  the  lip,  and  extending  backward  nearly  to  the  angle  of 
/the  jaw  (Fig.  202).    A  rubber  band  was  substituted  for  the  bandage, 


4i: 


MECHANICAL    DENTISTRY. 


and  extended  from  one  steel  wire  under  the  jaw  to  the  other,  out- 
side of  the  gutta-percha  chin  piece. 

May  19.  Interdental  splint  adjusted  (Fig.  203).  Patient  removed 
this  five  hours  later,  on  account  of  considerable  pain  on  the  right 
side  of  the  symphysis. 

May  20.  A  very  tender  induration  appeared  posterior  to  and  below 
the  cuspid  and  first  bicuspid  of  the  right  side.  On  opening  this,  a 
small  piece  of  bone  was  found  and  removed. 

May  21.  Splint  readjusted.    Patient  ate  and  slept  well. 

May  23.  Splint  again  removed  by  patient,  as  he  could  not  endure 

Fig.  203. 


the  pressure.  Bandage  applied,  which  imperfectly  held  the  frag- 
ments. 

May  28.  Interdental  splint  readjusted  and  fragments  placed  in 
position.    Wound  under  the  chin  nearly  healed. 

During  a  period  of  ten  days  after  the  readjustment  of  the  appli- 
ance,  it  was  found  necessary  occasionally  to  remove  the  chin  piece 
for  some  hours,  owing  to  extreme  pain  and  tenderness  of  the  ex- 
ternal surface.  Cotton  and  a  bandage  were  temporarily  substituted 
for  the  chin  piece  and  rubber  band.  Both  pain  and  tenderness  were 
partly  caused  by  the  pressure  requisite  to  retain  the  fragments  and 
splint  in  position.  The  splint  was  constantly  worn,  except  at  such 
times   as   were  necessary   to   remove   it   for   cleansing.     After  two 


APPLIANCES  FOR  THE  CORRECTION   OF  FRACTURED   MAXILLAE.   413 

months,  firm  union  was  found  to  have  taken  place,  and  occlusion 
of  the  teeth  correct.  This  case  appears  in  an  article  written  by  Dr. 
N.  W.  Kingsley,  published  in  Johnston's  Miscellany,  in  January, 
1874,  wherein  Dr.  Kingsley  gives  Dr.  Gibson  (who  was  at  that  time 
his  assistant)  credit  for  making  and  adjusting  the  splint. 

Case  4. — Male,  aged  about  sixty.  Lower  jaw  fractured  on  the 
right  side,  between  the  bicuspids.  Previous  to  admission  to  hospital 
he  had  been  treated  with  gutta-percha  covering  the  teeth,  and  a  four- 
tailed  bandage.  About  four  weeks  after  the  accident  these  were 
removed,  as  union  had  taken  place,  but  upon  examination  all  the 
teeth  to  the  left  of  the  fracture,  back  to  the  wisdom  tooth,  were 
found  to  be  displaced  downward  from  V2.  to  %.  of  an  inch  (Fig.  204). 

Impressions  were  taken,  and  a  splint  made  similar  to  that  de- 
scribed in  Case  3.     The  patient  was  etherized  and  the  jaw  refractured 

Fig.  204. 


at  the  same  point.  The  splint  was  adjusted  and  held  in  position  as 
in  Case  3.  About  twenty-four  hours  after  the  adjustment  of  the 
appliance,  the  patient  complained  of  numbness  extending  from  the 
point  of  fracture  to  the  symphysis.  On  examination,  after  the  re- 
moval of  the  chin  piece,  it  was  thought  that  this  was  due  to  an 
injury  of  the  nerve  at  or  near  the  mental  foramen.  It  remained  for 
some  weeks,  but  eventually  normal  sensation  was  regained. 

The  splint  was  worn  with  comfort  for  six  weeks,  the  chin  piece 
being  occasionally  removed  for  the  purpose  of  cleansing.  Occlu- 
sion of  teeth  was  found  correct  at  this  time. 

Case  5. — Male,  aged  thirty.  Lower  jaw  fractured  at  the  symphy- 
sis. The  left  central  incisor,  being  loose,  was  removed.  The  right 
fragment  was  displaced  downward  and  inward;  the  left  inward. 

The  splint  used  in  this  case  was  similar  to  the  one  last  described, 


414 


MECHANICAL   DENTISTRY. 


except  that  for  the  steel  wire,  gutta-percha  chin  piece,  and  rubber 
band,  an  external  metal  compress  was  substituted.  This  was  con- 
structed from  a  saw-frame  such  as  is  used  by  mechanical  dentists 
(Fig.  205).  To  this  was  attached  a  revolving  brass  chin  piece  (Figs. 
206  and  207)  ;  this  was  padded  with  spongiopilin  covered  with  oiled 
silk  (Fig.  208).  The  splint  was  worn  four  weeks,  when  occlusion 
of  the  teeth  was  found  to  be  correct. 

This  external  metal  compress  was  found  to  be  simpler  in  its  con- 
struction, more  readily  applied,  and  more  effective.     The  chin  piece 

Fig.  205. 


The  handle  and  the 
parts  marked  A, 
B,  were  re- 
moved. 


C,  revolving  brass  chin  piece.  The 
rod  at  D,  the  point  of  contact 
with  the  lips,  is  made  round  to 
avoid  irritation,  and  at  E  is  split 
and  bent  to  nearly  conform  to 
the  contour  of  the  jaw  and  teeth. 
To  this   (E)    is  attached  the  vul- 


Vulcanite  attached. 
The  top  holes 
serve  for  ascer- 
taining if  splint 
and  fragment  are 
in  position ;  the 
side  holes  are  for 
cleansing. 


should  be  made  of  any  size  or  form  the  case  may  require.  If  there 
are  external  wounds  or  abscesses,  holes  should  be  cut  in  the  chin 
piece  corresponding  with  these,  thus  permitting  drainage  and  treat- 
ment. 

For  the  reduction  or  retention  of  any  fracture  of  the  lower  jaw, 
with  much  displacement,  and  where  external  pressure  is  required, 
this  form  of  splint  will  prove  as  effective  as  any  appliance  that  may 
be  employed.  When  used,  it  is  not  always  necessary  completely  to 
reduce  the  fracture  at  the  time  of  introduction.    The  use  of  the  jaw 


APPLIANCES  FOR  THE  CORRECTION  OF  FRACTURED   MAXILLAE.  415 

for  masticating  will  gradually  cause  a  proper  adjustment  of  the 
teeth  to  the  splint. 

Case  6. — Male,  aged  about  forty.  Lower  jaw  fractured  at  the 
symphysis.  Left  side  displaced  downward  about  %  of  an  inch  and 
carried  inward.  Appliance  similar  to  that  last  described.  Frac- 
ture reduced  without  any  difficulty.  After  wearing  the  splint  four 
weeks,  occlusion  of  the  teeth  was  found  to  be  normal. 

Case  7. — Male,  fifty-two  years  of  age ;  while  assisting  in  launch- 

Fig.  208. 


Appliance  in  position    (from  photograph   of  patient). 


ing  a  ship,  was  struck  by  a  heavy  bar  across  the  left  side  of  the  face. 
Admitted  as  a  patient  to  Bellevue  Hospital. 

Examination  revealed  a  lacerated  wound  an  inch  long,  situated 
Ya,  of  an  inch  above  the  right  angle  of  the  mouth.  The  lower 
jaw  was  fractured  in  three  places  :  First,  at  the  end  of  the  sym- 
physis, between  the  central  and  lateral  incisors ;  second,  at  the 
right  of  the  symphysis,  between  the  central  and  lateral  incisors; 
third,  at  the  angle  back  of  the  last  molars,  right  side.     The  anterior 


416  MECHANICAL   DENTISTRY. 

fragment  was  displaced  downward  and  backward,  and  the  large 
fragment  on  the  right,  containing  six  teeth,  was  depressed  at  the 
anterior  end,  much  elevated  at  the  posterior.  No  displacement  of 
the  left  side  of  the  jaw. 

The  wound  in  the  lip  was  closed  with  silk  sutures,  and  a  four- 
tailed  bandage  applied  to  the  jaw,  but  a  few  days'  trial  proved  its 
inefficiency.  Impressions  were  then  taken  for  an  interdental 
splint.  Upon  removing  impression  of  the  upper  jaw,  this  also  was 
found  to  be  fractured  as  follows :  first,  from  behind  the  second 
bicuspid  on  the  right  side  across  the  roof  of  the  mouth,  through 
the  alveolar  process  on  the  left  side,  where  the  first  molar  had  been 
extracted,  then  around  in  front,  above  the  teeth,  to  the  right  side; 
second,  between  the  central  and  lateral  incisors  of  the  right  side, 

Fig.  209. 


running  along  the  median  line  and  intersecting  the  fracture  before 
described  (Fig.  209).  The  two  fragments  containing  all  the  teeth 
anterior  to  the  molars  were  slightly  displaced.  These  fractures 
were  readily  readjusted  and  held  with  ligatures. 

For  the  lower  jaw  the  splint  similar  to  that  used  for  Case  5  was 
applied  March  9th,  with  the  exception  that  the  tongue-holder  or 
duct  compressor  (used  by  dentists)  was  substituted  for  the  saw- 
frame;  the  chin  piece  padded  with  spongiopilin  covered  with 
oiled  silk.  From  that  date  the  patient  experienced  no  discomfort, 
and  ate  the  ordinary  hospital  food  without  difficulty  (Figs.  210  and 
211).  On  March  20th  he  was  discharged  from  the  hospital,  and  on 
April   10th  the  splint  was  removed.     No  deformity  remained. 

This  case  appears  in  Dr.  N.  W.  Kingsley's  article  published  in 
Johnstons  Miscellany,  February,  1874;  also  in  his  work  on  "Oral 


APPLIANCES  FOR  THE  CORRECTION  OF  FRACTURED   MAXILLAE.  417 

Deformities."  From  the  former  we  quote :  "  The  impressions,  cast, 
and  adaptation  of  this  instrument  were  made  by  my  assistants, 
Messrs.  Gibson  and  W.  H.  Kingsley." 

Fig.  210. 


Case    8. — Patient,    a    policeman,    aged    thirty-five.     Lower    jaw 
fractured    on    right    side,    between    second    bicuspid    and    second 


Fig. 


Appliance   in   position    (from   photograph   of   patient). 

molar;  the  first  molar  having  been  extracted,  third  molar  missing. 
An  attempt  had  been  made  to  reduce  and  hold  the  fracture  by  cov- 

27 


41 8  MECHANICAL   DENTISTRY. 

ering  the  teeth  with  gutta-percha  and  supporting  the  jaw  with  a 
four-tailed  bandage. 

Twenty  days  after  the  injury  was  received,  on  taking  impressions 
for  an  interdental  splint,  it  was  discovered  that  there  was  no  actual 
displacement  of  the  anterior  fragment,  but  the  posterior  one,  in- 
cluding the  second  molar,  was  elevated  about  ^4  0I  an  inch,  the 
tooth  coming  in  contact  with  the  third  molar  on  the  upper  jaw. 
The  treatment  was  similar  to  that  used  in  Case  7,  and  the  fracture 
was  reduced  without  any  difficulty.  The  splint  was  worn  with 
comfort  for  thirty  clays.     On  removal,-  the  teeth  occluded  correctly. 

Case  p. — Male,  aged  about  twenty-five,  subject  to  epileptic  con- 
vulsions. Fracture  due  to  a  fall  during  one  of  these  attacks.  The 
lower  jaw  was  fractured  at  the  symphysis;  right  side  displaced 
downward  about  y^  of  an  inch ;  anterior  end  of  fragment  outward ; 
posterior  portion  of  jaw  inward  about  *4  OI  an  inch.  No  displace- 
ment of  left  side  of  the  jaw.  An  attempt  had  been  made  to  reduce 
and  hold  the  fragments  in  position  with  gutta-percha  covering  the 
teeth,  and  a  four-tailed  bandage. 

Two  weeks  after  the  accident  impressions  were  taken  for  an  inter- 
dental splint,  which  was  applied,  the  fracture  being  reduced  with- 
out any  difficulty.  The  splint  was  worn  with  comfort  for  five  weeks, 
when  it  was  removed,  occlusion  of  the  teeth  being  correct.  A  few 
minutes  after  the  removal  of  the  splint  the  patient  had  an  epileptic 
seizure,  although  he  had  been  free  from  these  attacks  during  the 
treatment  for  fracture.     Appliance  similar  to  Case  8. 

Case  10. — Patient,  a  boy,  aged  six.  Two  fractures  of  the  lower 
jaw.  First,  between  the  lateral  incisor  and  cuspid,  left  side;  sec- 
ond, back  of  last  temporary  molar  on  right  side.  Displacement  of 
anterior  fragment  downward  and  inward,  each  about  %  of  an 
inch ;  slight  displacement  of  posterior  fragment ;  no  displace- 
ment of  left  side  (Fig.  212).  The  splint  used  was  similar  to  the  one 
in  Case  7,  with  necessary  alterations  (Fig.  213). 

Attempts  had  been  made  to  reduce  and  hold  the  fragments,  first, 
with  ligatures  about  the  teeth ;  second,  with  gutta-percha  covering 
the  teeth  and  a  bandage,  neither  of  which  proved  effectual. 

Three  weeks  after  the  accident  an  interdental  splint  was  adjusted. 
Great  difficulty  was  encountered  in  reducing  this  fracture.  A  few  days 
later,  the  reduction  not  being  satisfactory,  the  splint  was  removed, 
nitrous  oxid  administered,  fracture  reduced,  and  splint  replaced. 


APPLIANCES  FOR  THE  CORRECTION  OF  FRACTURED   MAXILLAE. 


419 


The  following  form  of  appliance  has  been  adopted  as  best  meet- 
ing the  requirements  of  cases  needing  an  external  metal  compress. 
It  consists  of  three  parts  :  First,  a  compressor ;  second,  a  chin  piece ; 
third,  an  inner  steel  band  or  the  wire  splint,  as  shown  in  Fig.  214. 

First,  the  compressor  (used  without  alteration  for  all  cases),  con- 


FlG. 


Fig.  213. 


Fig.  214. 


sisting  of  a  horizontal  rod  (A)  and  a  vertical  rod  (B),  each  about 
two  inches  in  length,  meeting  at  right  angles.  Rod  B  is  hollow, 
and  at  its  upper  end  is  fitted  a  thumb-screw  so  adjusted  as  to  hold 
at  any  point  in  it  a  movable  rod  (C),  thus  regulating  pressure. 
Passing  horizontally  through  a  bulb  at  top  of  rod  C  is  a  rod  (D) 
three  inches  in  length,  bent  downward  at  right  angles  for  about  an 
inch.  One-half  of  this  lower  end  is  smaller 
in  diameter  than  the  other  half,  leaving  a 
shoulder.  A  thumb-screw  in  the  bulb  admits 
of  the  adjustment  of  rod  D  at  any  angle. 

Second.  The  chin  piece  is  attached  to  the 
compressor  by  a  thumb-screw,  so  adjusted 
that  it  may  be  pushed  backward  and  forward 
on  the  rod  A,  and  at  the  same  time  affording 
a  double  rotary  movement.  The  chin  piece 
is    made    in    different    forms,    each    peculiarly 

adapted  to  the  location  of  fracture,  (a)  If  fracture  is  at  or  near 
the  symphysis,  the  chin  piece  consists  simply  of  a  flat  piece  of 
brass  placed  directly  under  the  chin;  (b)  if  back  of  the  cuspid 
teeth  involving  the  molars,  it  should  fit  the  chin  extending  back  to 
the  angle  of  the  jaw;  (c)  if  involving  both  the  angle  and  the  con- 
dyle, it  must  include  the  entire  lower  jaw,  and  extend  to  the  line 


420  MECHANICAL    DENTISTRY. 

of  the  ear.  A  metal  button  (E)  should  be  attached  on  each  side  of  the 
chin  piece  for  use  in  attaching  any  necessary  support.  For  support 
nothing  surpasses  a  skull-cap,  to  each  side  of  which  can  be  attached 
a  piece  of  elastic  reaching  to  the  chin  piece ;  this  in  turn  can  be 
fastened  to  the  metal  button  by  a  ring  sewed  in  the  end  of  the  elastic. 

Third.  The  inner  steel  bands  are  made  of  various  sizes  and  shapes 
to  conform  as  nearly  as  possible  to  the  contour  of  the  jaw  and  teeth, 
and  are  vulcanized  in  the  splint. 

This  appliance  has  been  so  constructed  that  the  external  compress 
may  be  removed  independent  of  the  splint  proper ;  temporarily  where 
external  wounds  or  abscesses  need  treatment;  permanently  where 
there  is  sufficient  union  to  retain  fragments. 

Any  irritation  of  the  lips  caused  by  the  adjustment  of  the  rod  at 
the  median  line  may  be  remedied  by  removing  (the  patient  having 
previously  closed  the  jaws  firmly)  the  external  compress  and  read- 
justing it  at  any  point  to  the  right  or  left. 

Splintage  for  Section  of  Inferior  Maxilla. — In  certain  opera- 
tions designed  to  reach  the  zygomatic  fossa  and  in  external  pharyn- 
gectomy  an  interdental  splint  has  been  employed  with  much  satis- 
faction. A  very  interesting  case  in  point*  is  that  treated  by  George 
R.  Fowler,  M.D.,  Professor  of  Surgery  in  the  New  York  Polyclinic, 
and  Rodriguez  Ottolengui,  M.D.S.,  of  New  York.  After  some 
preliminary  remarks  upon  different  methods  of  procedure,  or  forms 
of  operations,  Dr.  Fowler  says  that  section  of  the  maxilla,  as  hereto- 
fore accomplished,  has  consisted  in  dividing  the  bone  either  just 
above,  or  in  front  of  the  angle,  i.  c,  either  through  the  ramus,  in 
which  case  the  saw-cut  runs  in  a  horizontal  direction,  or  through 
the  body  of  the  bone,  the  section  being  made  vertically.  These 
sections  were  first  proposed  by  Mikulicz,  to  which  he  added,  in  cases 
of  external  pharyngectomy,  removal  of  a  portion  or  the  whole  of 
the  ascending  process,  or  ramus  of  the  jaw.  The  latter  is  usually 
an  unnecessary  mutilation  and  seriously  interferes  with  the  func- 
tions of  the  jaw,  as  well  as  leading  to  an  unsightly  appearance  of 
the  parts.  If  the  section  is  made  in  front  of  the  angle  and  in  a 
vertical  direction,  the  angle  itself  is  in  the  way  of  complete  access 
to  the  parts  above  the  •  latter,  an  important  consideration  both  in 
neurectomy  at  the  foramen  ovale,  and  in  external  pharyngectomy. 

*  Reported  in  the  Items  of  Interest,  January,   1897. 


APPLIANCES  FOR  THE   CORRECTION   OF   FRACTURED   MAXILLAE.   42 1 

In  order  to  overcome  these  objections,  Dr.  Fowler  makes  an 
oblique  section  directly  across  the  angle  itself.  This  is  done  with 
a  chain  saw,  the  attachments  of  the  masseter  upon  the  external, 
and  those  of  the  internal  pterygoid  upon  the  internal  surface  of  the 
jaw,  being  first  detached.  The  soft  parts  are  raised,  together  with 
the  periosteum,  which  is  stripped  from  the  outer  and  inner  surface 
of  the  bone  by  means  of  the  rugine  or  raspatory.  The  chain  saw 
is  passed  beneath  the  periosteum,  and  the  cut  commenced  just  pos- 
terior to  the  site  of  the  wisdom  tooth.  The  jaw  is  steadied  by  an 
assistant,  and  the  chain  saw  so  directed  that  the  cut  shall  terminate 
at  the  point  of  the  angle.  By  this  means  an  oblique  section  is 
made  across  the  angle,  and  a  result  produced,  when  readjustment 
of  the  divided  bony  parts  is  effected,  not  unlike  what  is  known 
among  mechanics  as  a  "  miter."  The  advantages  gained,  in  the 
way  of  access  to  the  deeper  parts,  are  beyond  question,  and  are 
illustrated  in  Fig.  215. 

In  the  case  of  a  young  lady,  operated  on  for  the  removal  of  a 
sarcoma  of  the  tonsil  and  its  neighborhood,  it  was  determined  to 
overcome,  if  possible,  the  disadvantages  which  constituted  the  ob- 
jectionable features  of  the  older  methods  of  bone  section,  and  re- 
adjustment of  the  fragments  and  the  maintaining  of  the  same  in 
their  proper  relations.  In  furtherance  of  this  desire,  Dr.  Fowler 
conceived  the  idea  of  having  a  proper  interdental  splint  made  pre- 
liminarily, which  could  be  applied  immediately  after  the  completion 
of  the  operation,  and  which  should  automatically  adjust  the  divided 
parts  and  maintain  them  in  their  proper  relations,  thus  assuring  a 
perfect  restitution  of  their  physiological  functions. 

Accordingly,  a  few  days  prior  to  the  operation  he  called  into 
requisition  Dr.  Ottolengui,  whose  ready  appreciation  of  the  neces- 
sities of  the  case  proved  to  be  invaluable  in  carrying  the  latter  to  a 
most  successful  termination,  so  far  as  the  mechanical  difficulties  to 
be  overcome  were  concerned.  The  necessary  casts  were  obtained 
and  an  interdental  splint  constructed. 

All  being  in  readiness,  the  operation  of  external  pharyngectomy, 
with  oblique  section  of  the  jaw  at  the  angle,  was  performed.  Upon 
the  completion  of  the  operation,  the  bony  parts  were  readjusted. 
It  was  found  that  the  two  halves  of  the  obliquely  divided  ramus 
and  body  of  the  jaw  fitted  together  like  the  united  corners  of  a 


4^2 


MECHANICAL    DENTISTRY. 


picture    frame,    the    comparatively    long    cut    and   the    broad    bony 
surfaces  aiding  this  materially. 

Fig.  215. 


1.  Hyoglossus  muscle.  2.  Retracted  posterior  belly  of  the  digastric.  3-  Stylo- 
hyoid muscle  divided  at  its  lower  and  anterior  attachment  at  4.  5-  Mylo- 
hyoid muscle,  retracted  anteriorly.     6.  Body  of  inferior  maxilla. 


But  as  it  was  subsequently  discovered  that  the  slight  separation 
of  the  jaws  which  the  interdental  splint  produced  displaced  the 
body  of  the  bone  in  a  forward  and  downward  direction,  and  sepa- 


APPLIANCES  FOR  THE  CORRECTION  OF  FRACTURED   MAXILUE.   423 

rated  the  fragments,  it  at  once  became  evident  that  a  splint  was 
needed  which  would  admit  of  adjustment  of  the  tooth  surfaces  to 
each  other  with  the  minimum  amount  of  intervening  space.  This 
was  undertaken  and  successfully  accomplished  by  Dr.  Ottolengui. 

The  patient  was  fed  at  first  by  a  tube  led  through  the  external 
wound  and  into  the  pharynx.  Through  this  tube,  also,  frequent 
irrigations  of  the  parts  with  potassium  permanganate,  as  well  as 
the  application  of  peroxid  of  hydrogen  solution,  were  carried  on. 
Subsequently  the  feeding  and  irrigation  were  effected  by  means  of 
a  soft  rubber  catheter  passed  between  the  metal  splint  and  cheek, 
and  into  the  pharynx. 

The  splint  was  dispensed  with  in  the  third  week  and  movements 
of  the  jaw  permitted.  The  healing  was  uneventful,  and  the  masti- 
catory function  of  the  jaw,  despite  the  fact  that  the  callus  thrown 
out  in  the  reparative  process  was  at  the  site  of  the  attachments  of 
the  internal  pterygoid  and  masseter  muscles,  was  complete.  A 
point  worthy  of  note  in  the  case  is  the  fact  that  almost  perfect 
restoration  of  phonation  finally  took  place,  despite  the  fact  that  in 
the  operation  for  the  removal  of  the  diseased  parts  it  became  neces- 
sary to  remove,  in  addition  to  the  tonsil  and  underlying  parts,  all 
of  the  faucial  pillar  and  at  least  three-fourths  of  the  velum.  The 
cicatricial  contraction  which  followed  the  healing  process  upon  the 
diseased  side,  displaced  toward  the  median  line  the  remains  of  the 
velum.  The  effect  of  this,  as  well  as  the  control  over  the  move- 
ments which  the  patient  obtained,  was  finally  sufficient  to  produce 
occlusion  of  the  postnasal  space,  and  overcome  to  a  great  extent 
the  nasal  sound  of  the  voice  which  at  first  was  quite  marked. 

After  constructing  and  inserting  a  modified  form  of  the  Gunning 
splint,  which  seemed  to  fit  accurately  and  comfortably,  the  divided 
jaw  was  held  in  position  by  a  series  of  bandages  which  covered  the 
head,  as  well  as  the  dressings  over  the  wound  in  the  neck,  and 
passing  around  and  under  the  chin.  This,  however,  as  has 
been  stated,  proved  ineffectual,  and  Dr.  Ottolengui  describes 
the  peculiarities  of  the  case  from  this  stage,  as  follows :  "  Two 
days  later  I  was  called  to  visit  the  patient,  as  she  was  suffering 
considerably  from  the  splint.  With  some  chagrin  I  visited  the 
hospital,  and  upon  examination  discovered  that  in  the  region  of  the 
wound  all  the  soft  parts  had  become  so  much  swollen  that  the 
splint,  which  at  first  did  not  touch  the  gum  tissue  at  any  point,  was 


424 


MECHANICAL   DENTISTRY. 


now  in  contact  with  it,  and  had  already  caused  a  most  painful 
abrasion.  Had  this  been  the  only  fault  in  the  splint  it  would  have 
been  trivial  in  importance,  easily  remedied  by  cutting  away  all  of 
that  part  of  the  splint  which  engaged  the  lower  molars  of  that  side, 
which  I  did,  the  splint  being  perfectly  comfortable  when  replaced. 
Nevertheless  I  record  this  fact,  as  worthy  to  be  remembered  by  all 
who  may  choose  to  make  an  interdental  splint  of  rubber,  especially 
when  through  neglect  an  operation  shall  have  become  necessary  in 
order  to  bring  the  ends  of  the  bones  together,  in  order  to  introduce 
the  splint.  After  all  such  surgical  interference  it  is  well  to  remem- 
ber that  swellings  may  occur  immediately  in  the  region  of  the  frac- 
ture, and  special  caution  should  be  taken  to  avoid  impingement  of 
the  splint  in  this  vicinity. 

"  But  an  examination  of  the  parts,  while  I  had  the  splint  out,  sud- 
denly aroused  a  suspicion  in  my  mind,  which,  if  true,  would  prove 
that  the  splint  was  inherently  wrong  in  principle.  This  visit  being 
at  night,  I  allowed  the  house  surgeon  to  replace  the  splint  and 
bandages,  and  arranged  for  a  consultation  with  Dr.  Fowler  for  the 
following  morning,  which  fortunately  was  Sunday,  so  that  I  had  the 
whole  day  at  my  disposal.  At  this  examination  we  found  to  our 
regret  that  my  suspicion  was  well  founded,  and  that  the  splint 
would  prove  harmful ;  consequently  a  splint  of  an  entirely  new  de- 
sign was  decided  upon. 

"  The  fault  in  the  splint  lay  in  the  opening  of  the  jaws.  The  main 
object  of  a  splint,  aside  from  obviating  the  necessity  of  wire  suture, 
is  to  hold  the  jaws  during  the  processes  of  union  in  such  position 
that  subsequently  the  occlusion  will  be  correct.  The  double  in- 
terdental splint  was  specially  designed  to  this  end,  and  has  un- 
questionably accomplished  the  purpose  in  hundreds  of  cases,  but 
these  cases  have  been  fractures  of  the  bodies  of  the  bones,  the  rami 
being  unaffected.  /  have  little  doubt  now,  that  in  cases  where  the 
ramus  has  been  involved,  perfect  occlusion  has  not  resulted,  and 
moreover  that  it  has  remained  unsuspected  that  the  splint  actually  pre- 
vented such  occlusion.  In  the  case  of  our  patient,  we  found  that  the 
interposition  of  the  splint  caused  a  V-shaped  gaping  of  the  divided 
parts,  and  it  was  an  unavoidable  deduction  from  the  premises  that 
union  would  result  from  the  deposition  of  new  bone  to  fill  this  gap, 
so  that  after  healing,  while  the  jaws  would  accurately  occlude  with 
the  interdental  splint,  the  splint  being  removed,  the  additional  bone 


APPLIANCES  FOR  THE  CORRECTION   OF  FRACTURED   MAXILLAE.   425 

deposited  in  the  ramus  would  preclude  the  possibility  of  perfect  occlu- 
sion of  the  teeth,  each  set  with  the  other." 

Ottolengui's  Splint. — "  Under  these  circumstances  I  obtained 
new  impressions  of  the  jaws,  and  hurried  from  the  hospital  in  Brook- 
lyn to  my  office  in  New  York,  arriving  in  the  laboratory  at  one 
o'clock.  I  started  again  for  the  hospital  at  five  o'clock,  carrying  the 
completed  splint  with  me.  I  mention  this  as  an  indication  of  what 
may  be  done  in  an  emergency.  Models,  dies,  and  counter-dies  are 
then  made.  Using  20-carat  gold,  29  gage,  I  struck  up  a  continuous 
cap  to  cover  all  of  the  teeth  in  each  jaw,  in  the  incisive  region,  how- 
ever, extending  only  over  the  cutting  edges.  The  plaster  models, 
with  the  gold  covering  the  teeth,  were  then  occluded,  and  the  two 
caps  fastened  together  with  hard  wax.     They  were  then  invested  and 

Fig.  216. 


permanently  united  with  solder.  It  may  be  useful  to  record  a  little 
trick  in  connection  with  the  soldering,  which  saved  a  great  deal  of 
time.  Of  course  the  teeth  of  two  jaws  do  not  occlude  like  cog- 
wheels, consequently  these  gold  caps  were  found  to  be  in  contact 
at  some  points,  while  spaces  appeared  at  others.  I  took  a  piece  of 
platinum  wire  and  cut  it  into  small  bits,  which  I  bent  into  suitable 
curves  and  dropped  into  the  spaces.  These  bits  of  wire  served  as 
leaders  for  the  solder,  which  flowed  like  water,  closing  the  seam 
throughout  its  entire  extent.  Fig.  216  shows  the  form  of  this 
double  interdental  splint,  made  of  gold. 

"  I  mentioned  that  in  the  incisive  region  the  splint  extended  only 
slightly  over  the  cutting  edges.  There  was  a  useful  purpose  in 
this,  which  is  comprehensively  shown  in  Fig.  217  where  the  splint 


426  MECHANICAL   DENTISTRY. 

is  seen  as  it  appeared  in  the  mouth.  Had  the  labial  surfaces  of  the 
anterior  teeth  been  covered  as  well  as  the  buccal  surfaces  of  the 
posterior  teeth,  it  would  have  been  impossible  to  know  positively 
that  the  jaws  were  properly  in  place  within  the  splint;  whereas  by 
cutting  away  the  gold  from  the  faces  of  the  anterior  teeth,  so  that 
no  gold  whatever  covered  those  surfaces,  it  could  be  determined 
readily,  and  at  all  times,  whether  the  jaws  were  properly  in  position. 
In  this  respect  the  illustration  is  not  perfect,  as  the  artist  has  de- 
picted the  gold  extending  somewhat  upon  the  labial  surfaces, 
whereas  in  this  region  no  gold  whatever  was  visible,  except  that 
actually  between  the  cutting  edges  of  the  teeth  of  the  opposite 
jaws.  This  feature  was  shown  to  be  of  considerable  value,  as  the 
tendency  of  the  tired  jaws  will  be  to  open,  and  these  frequent  efforts 
may  stretch  the  bandages,  thus  allowing  play  to  the  mouth,  which, 

Fig.  217. 


however,  is  readily  detected  by  the  attendant,  who  may  ask  the 
patient  occasionally  to  endeavor  to  open  the  mouth,  whereupon  it 
can  be  observed  whether  the  teeth  move  from  their  places  in  the 
splint,  in  which  case  the  bandages  can  be  tightened. 

"  This  splint,  when  placed  in  position,  caused  absolutely  no 
discomfort  to  the  patient,  was  clean,  free  from  odor  at  all  times 
and  proved  to  be  all  that  could  be  desired.  The  long  advo- 
cated feeding  space  was  not  missed,  because  at  first  the  patient 
was  fed  through  the  tube  which  entered  the  mouth  through  the 
wound,  and  subsequently  through  a  catheter  which  passed  back 
between  the  cheek  and  jaws,  entering  the  mouth  behind  the  molars, 
the  patient  finding  no  difficulty  to  draw  it  in  with  the  tongue,  and 
to  obtain  liquids  by  suction." 

So  far  as  the  records  show  this  was  the  first  use  of  a  double 


APPLIANCES  FOR  THE  CORRECTION  OF  FRACTURED   MAXILLAE.   427 

interdental  splint,  bringing  the  jaws  into  close  occlusion,  and 
abandoning  the  theory  of  the  feeding  space.  As  a  division  of  the 
jaw  at  the  ramus  offers  more  difficulties  than  a  fracture  in  the  body 
of  the  bone,  and  as  this  form  of  splint  is  here  shown  to  be  ade- 
quate in  such  cases,  there  can  be  no  necessity  hereafter  for  open- 
ing the  jaws  and  thus  stretching  and  tiring  the  muscles,  which  by 
the  method  here  advocated  are  all  at  rest. 

Angle's  Method  of  Fixation. — A  comparatively  recent  and  ex- 
cellent method  for  treatment  of  fractures  of  the  maxillae  is  that  de- 
vised by  Dr.  E.  H.  Angle,  of  Minneapolis,  and  through  the  doctor's 
courtesy  I  am  enabled  to  give  a  full  description  of  his  methods  and 
appliances  here.  He  says :  "  The  methods  used  by  myself  in  treat- 
ing fractures  of  the  maxillae  have  been  so  successful  and  so  gratify- 
ing that  it  would  seem  they  approach  for  efficiency  and  simplicity 
more  nearly  the  ideal  than  any  yet  devised." 

In  order  that  this  system  of  treating  fractures  of  the  maxillary 
bones  may  be  more  easily  understood,  we  will  divide  them  into 
three  classes.  The  first  class  comprises  all  simple  fractures  in 
which  the  teeth  are  good  and  sufficiently  firm  in  their  attachments 
(especially  on  each  side  of  the  fracture)  to  afford  anchorage  for  the 
appliance. 

The  second  class  comprises  all  fractures  where  the  teeth  are  un- 
suited,  from  disease  or  any  other  cause,  for  anchorage,  but  yet  suffi- 
cient to  give  the  correct  articulation  of  the  jaws. 

The  third  class  comprises  all  fractures  where  the  jaws  are  edentu- 
lous. The  following  cases,  treated  by  Dr.  Angle,  will  enable  the 
reader  to  comprehend  the  method  peculiar  to  each  class : 

Case  No.  i  will  illustrate  class  No.  I.  A  young  man  fell  from 
a  pile  of  lumber,  a  distance  of  15  or  20  feet,  and,  besides  severe 
bruises,  suffered  a  simple  fracture  through  the  symphysis,  termi- 
nating, however,  in  front  between  the  central  and  lateral  on  the 
left  side,  as  shown  by  the  line  in  the  engraving  (Fig.  218). 

Upon  examination,  it  was  found  that  the  fractured  bone  was  quite 
widely  separated  at  the  top,  and  the  left  central  incisor  was  loosened. 
The  treatment  practised  was  as  follows :  The  ends  of  the  fractured 
bones  were  placed  in  their  proper  position  and  temporarily  fastened 
by  lacing  the  teeth  with  silk  ligatures.  Bands  of  very  thin  German 
silver  were  made  to  encircle  and  accurately  fit  the  cuspid  teeth.  A 
small  tube  of  German  silver,  y2  of  an  inch  in  length,  was  soldered 


428 


MECHANICAL   DENTISTRY. 


to  each  band  and  in  exact  alignment;  a  piece  of  wire  accurately 
fitting  the  bore  of  these  tubes,  bent  at  right  angles  at  one  end  and 
having  a  screw  cut  upon  the  other  end,  was  slipped  through  each 
tube  and  secured  therein  by  adjusting  a  nut  on  the  screw.  The 
bands  were  cemented  in  position  upon  the  teeth  by  means  of  oxy- 
phosphate  cement,  as  shown  in  Fig.  218. 

After  the  cement  had  become  thoroughly  set,  the  nut  was  then 
tightened  until  the  fractured  ends  of  the  bone  were  drawn  snugly 
together. 

The  appliance  was  worn  without  displacement  or  trouble  for 
twenty-one  days,  when  it  was  removed,  the  bone  having  become 
firmly  united.  I  may  add,  that  during  the  time  the  appliance  was 
worn,  so  firmly  was  the  jaw  supported,  the  patient  suffered  little  if 
any  inconvenience,  and  after  the  third  day  partook  regularly  of  his 

Fig.  218. 


meals,  using  his  jaws  freely,  but,  of  course,  avoided  the  hardest 
particles  of  food.  After  removing  the  appliance  a  careful  impres- 
sion of  the  jaw  was  taken,  a  model  made,  and  the  appliance  trans- 
ferred to  the  model,  exactly  as  shown  in  the  engraving.  The 
lower  part  of  the  jaw  is,  of  course,  diagrammatic,  and  was  added 
by  the  engraver  to  show  the  line  of  fracture. 

It  should  be  borne  in  mind  that  the  principle  upon  which  this 
appliance  is  based  is  not  the  same  as  where  the  teeth  are  simply 
wired  together,  but  very  different ;  for  in  wiring,  the  upper  parts  of 
the  fracture  only  are  tipped  or  drawn  together,  and  no  pressure  or 
support  is  given  to  the  lower  parts,  while  in  the  method  here  shown 
it  will  be  seen  that,  by  reason  of  the  bands  and  pipes  being  rigidly 
attached  to  the  anchor  teeth,  tipping  is  impossible,  and  pressure  is 
exerted  equally  upon  both  parts  (upper  and  lower)  of  the  fracture 
as  they  are  drawn  together  by  the  screw. 


APPLIANCES  FOR  THE   CORRECTION   OF   FRACTURED   MAXILLAE.   429 

This  device  may  be  applied  in  any  locality  in  either  jaw,  provided 
suitable  teeth  for  anchorage  be  not  too  far  remote  from  line  of 
fracture.  The  screw  may  be  bent  to  accommodate  the  curve  of 
the  arch,  should  the  fracture  occur  in  the  region  of  the  cuspid. 

These  bands,  tubes,  wires,  screws,  and  nuts  are  some  of  the  ap- 
pliances known  as  "  Angle's  Regulating  and  Retaining  Appliances," 
devised  and  used  for  the  purpose  of  correcting  irregularities  of 
the  teeth.  They  may  be  procured  of  dealers  in  dental  goods.  (See 
Fig.  219.) 

The  treatment  for  cases  of  the  second  class  is  illustrated  in  the 
following  instance :  On  July  4,  1889,  a  man  aged  forty-five  was  ad- 
mitted to  the  Minneapolis  City  Hospital.     A  blow  from  a  police- 

Fig.  219. 


man's  club  had  produced  two  simple  fractures  of  the  inferior  max- 
illa. The  first  was  an  oblique  fracture  of  the  right  side,  beginning 
with  the  socket  of  the  second  bicuspid,  extending  downward  and 
backward,  involving  the  socket  of  the  first  molar,  breaking  out  the 
second  bicuspid,  and  greatly  loosening  the  first  molar.  The  second 
molar  had  been  lost  years  before,  while  the  third,  as  well  as  the  re- 
maining teeth,  were  much  abraded  and  loosened  by  salivary  cal- 
culus, thus  making  the  application  of  the  appliance  described  in 
Case  No.  1  impossible.  The  second  fracture  was  situated  on  the 
opposite  side  high  up  in  the  ramus. 

Because  of  swollen  condition  of  the  parts,  the  exact  line  of  frac- 
ture could  not  be  detected,  but  the  grinding  of  the  ends  of  the  bone 
and  the  great  pain  occasioned  thereby  were  unmistakable  evidences 


43° 


MECHANICAL    DENTISTRY. 


of  a  fracture.  The  patient,  as  in  all  such  cases,  was  unable  to  close 
the  jaws.  The  fracture  on  the  right  side  was  widely  separated, 
and  the  anterior  piece  much  depressed  by  reason  of  the  contraction 
of  the  depressor  muscles,  while  the  posterior  bone  was  drawn  firmly 
up,  the  molar  teeth  occluding.      (See  Fig.  220.) 

The  following  is  the  treatment  used :  Bands  were  made  to  encir- 
cle all  four  of  the  cuspid  teeth,  they  being  the  most  firmly  attached 
in  their  sockets.  The  fractured  ends  of  the  bones  were  placed  in 
apposition,  the  lower  jaw  closed  carefully.  The  occlusion  of  the 
lower  teeth  upon  the  upper  required  so  much  force  and  occasioned 
such  intense  pain  that  it  became  necessary  to  anesthetize  the 
patient.  Points  on  the  bands  for  the  necessary  attachments  were- 
carefully  noted.     The  bands  were  then  slipped  off  the  teeth,   and. 

Fig.  220. 


little  pipes  (shown  at  Fig.  219)  soldered  at  the  necessary  points,, 
after  which  the  bands  were  cemented  in  their  proper  position  upon 
the  teeth,  and  two  small  traction  screw-wires,  the  same  as  shown  at 
Fig.  219,  were  slipped  into  the  pipes.  The  jaws  were  closed  and  the 
nuts  tightened  on  the  screws,  until  the  jaws  were  drawn  firmly  to- 
gether, and  each  tooth  occupied  its  exact  position  in  occluding  upon 
its  fellow  of  the  opposite  jaw.  Both  fractures  were  then  carefully 
examined  and  found  to  be  in  perfect  apposition,  and  presented  the- 
appearance  shown  in  Fig.  220.  The  most  natural  position  for  the 
jaw  and  the  muscles  had  been  secured,  thus  placing  the  parts  in 
their  natural  positions  of  relaxation  and  rest. 

During  an  attack  of  coughing  during  the  night  following,  one  of 
the  bands  was  wrenched  loose,  but  was  replaced  the  next  day  with- 


APPLIANCES  FOR  THE   CORRECTION   OF   FRACTURED   MAXILLAE. 


431 


out  trouble.  No  further  accidents  occurred.  The  patient  readily 
took  nourishment  through  the  spaces  between  the  teeth.  Thus 
the  fractured  jaw  was  firmly  supported  without  the  least  motion  for 
twenty-two  days,  when  the  appliance  was  removed,  showing  most 
excellent  results. 

The  following  case  possesses  several  points  of  special  interest; 
the  fractures  were  in  regions  similar  to  the  case  just  described,  and 
the  appliances,  though  involving  similar  mechanical  principles,  will 
be  found  to  be  greatly  simplified. 

Thomas  B.  was  admitted  to  the  Dental  Infirmary  of  the  Univer- 
sity of  Minnesota,  suffering  from  the  effects  of  a  blow  received  on 
the  left  side  of  the  jaw  from  a  cant-hook  while  working  in  a  lum- 
ber camp  in  Wisconsin,  which  produced  fracture  of  the  jaw  in  two 
places.  The  first  fracture  was  on  the  left  side,  beginning  between 
the  first  and  second  bicuspids  and  extending  downward  and  back- 
ward, and  involving  the  lower  part  of  the  anterior  root  of  the  first 
molar.  The  second  fracture  was  on  the  right  side,  directly  through 
the  angle  of  the  jaw.  The  fractures  had  occurred  thirty-two  days  pre- 
vious to  his  admission  to  the  infirmary,  during  which  time  nothing 
had  been  done  to  reduce  them.  He  reported  that  he  had  called  upon 
a  physician,  who  supposed  the  trouble  was  merely  an  abscessed 
tooth,  and  had  lanced  the  gum  with  the  view  of  reducing  the  swell- 
ing. Later  the  patient  had  called  upon  a  dentist  in  one  of  the 
smaller  towns,  who  also  failed  to  diagnosticate  the  fracture,  and  ex- 
tracted both  bicuspids,  in  the  hope  of  giving  relief.  Upon  exami- 
nation I  found  considerable  swelling  in  the  region  of  this  fracture, 
with  the  usual  result ;  the  patient  being  unable  to  close  his  mouth 
by  reason  of  the  anterior  piece  of  the  fractured  bone  being  drawn 
down  by  the  contraction  of  the  depressor  muscles.  A  false  joint 
had  also  become  established,  and  the  bones  could  be  easily  worked 
without  causing  pain. 

At  the  point  of  fracture  on  the  right  side  there  was  little  or  no 
displacement;  the  swelling  was  also  slight. 

The  patient  was  anesthetized.  The  ends  of  the  bone  were 
then  rubbed  forcibly  together  with  the  view  of  breaking  up  the 
false  attachments  and  stimulating  activity  in  repair. 

The  ends  of  the  bones  were  now  placed  in  perfect  apposition, 
and  the  mouth  closed,  great  care  being  taken  to  articulate  the  teeth 
in  their  correct  position  against  the  upper  ones. 


432 


MECHANICAL   DEXTISTRY. 


Fig.  221. 


The  jaw  was  now  firmly  bound  in  this  position  to  the  upper 
teeth,  in  the  same  manner  as  described  in  Case  No.  2,  with  this 
difference,  that  the  method  was  improved  upon  and  simplified  by 
using  clasp  bands,  as  shown  in  Fig.  221.  No  cement  was  used,  and 
instead  of  the  screws  small  metallic  buttons  were  soldered  to  the 
sides  of  the  bands  (as  shown  in  the 
cut),  around  which  fine  binding  wire  was 
wrapped  in  the  form  of  a  figure  8.  (See 
Fig.  222.) 

The  bands  seen  upon  the  molar  teeth  in 
the  engraving  were  not  used  in  this  case, 
but  are  shown  for  the  purpose  of  illustrating  how  they  may  be  used 
in  case  of  comminuted  fracture.  At  the  end  of  seventeen  days  the 
bands  were  removed  and  the  patient  discharged,  the  bone  having 
been  firmly  united. 

Dr.  Angle  suggests  that  it  might  be  urged  as  an  argument  against 
this  method  that,  the  teeth  being  closed  and  the  jaws  being  firmly 
bound    together,    the    patient    would    be    unable    to    take    sufficient 


Fig. 


nourishment.  It,  however,  rarely  happens  that  a  patient  is  found 
without  some  teeth  missing,  thereby  leaving  abundance  of  space 
for  the  passage  of  liquid  foods,  and  even  if  all  the  teeth  were  sound 
and  in  perfect  position,  it  has  been  proved  that  there  is  plenty  of 
space  between  the  teeth  and  behind  the  molars  and  between  the 
upper  and  lower  incisors  for  taking  all  nourishment  necessary.     In 


APPLIANCES  FOR  THE  CORRECTION  OF  FRACTURED   MAXILLAE.   433 

such  cases  more  time  would  be  consumed  in  taking  nourishment, 
but  this  obstacle  is  compensated  for  by  the  main  points  of  advantage 
in  its  favor,  such  as  cleanliness  and  greater  comfort  to  the  patient, 
as  compared  with  the  many  bulky  and  awkward  appliances  in  use. 

Thirdly,  its  extreme  simplicity  enables  any  one  with  ordinary 
mechanical  ability,  when  provided  with  a  set  of  clamp  bands,  to 
easily  and  quickly  set  all  ordinary  cases  of  fracture. 

And,  lastly,  the  certainty  of  correct  results  will  be  sufficient  rea- 
son for  all  those  who  are  interested  in  this  branch  of  surgery  to  give 
it  a  trial.  Class  No.  3,  comprising  fractures  of  edentulous  jaws,  are 
fortunately  very  rare.  The  method  of  treatment  is  similar  in  prin- 
ciple to  that  already  described  in  class  No.  1,  only  that  in  place  of 
the  teeth  small  bone  hooks  are  used,  drilling  for  their  reception  a 
suitable  cavity  on  each  side  of  the  fracture,  comparing  in  position 
to  the  original  sockets  of  the  teeth,  the  same  as  if  the  operation  of 
implanting  teeth  were  intended;  the  cavities  thus  made  need  not 
be  nearly  so  large  or  deep.  They  should  also  be  drilled  obliquely, 
to  correspond  to  the  course  taken  by  the  hooks.  The  hooks  before 
insertion  should,  of  course,  be  made  antiseptic.  While  Dr.  Angle 
has  confidence  in  this  means  of  treatment  for  edentulous  jaws,  it 
seems  evident  to  the  writer  that  the  interdental  splint  already  de- 
scribed would  be  more  practicable. 


28 


CHAPTER  XXIX. 

APPLIANCES  FOR  THE  CORRECTION  OF  DENTAL  IRREGU- 
LARITIES. 

Orthodontia,  which  pertains  to  the  correction  of  irregularity  in 
the  position  of  the  human  teeth,  and  which  was  given  little  or  no 
attention  by  the  earlier  teachers,  is  now  recognized  as  a  distinct 
branch  or  specialty  of  dental  science.  To  practice  this  field  along 
the  advanced  lines  requires  special  study,  investigation,  and  training 
and  it  is  our  purpose,  in  the  present  chapter,  to  introduce  the  most 
important  methods  and  principles  involved,  with  the  manner  of  con- 
structing and  adjusting  the  appliances. 

Mechanical  Forces. — The  operator  in  orthodontia  has  an 
opportunity  to  utilize  his  knowledge  of  physics,  and  the  laws  of 
mechanics.  As  a  very  able  writer,  Dr.  Eugene  Talbot,  says : 
These  laws  are  founded  upon  the  action  of  simple  elements  which 
are  interposed  between  the  moving  power  and  the  resistance,  for 
the  purpose  of  changing  the  direction  of  the  force.  These  are 
called  mechanical  powers,  and  are  divided  into  two  primary  ele- 
ments, the  lever  and  the  inclined  plane.  The  principle  of  the  lever 
is  the  basis  of  the  pulley,  the  wheel,  and  axle.  That  of  the  inclined 
plane  is  the  basis  of  the  wedge  and  screw. 

Elasticity,  as  shown  in  India-rubber  and  the  spring  of  metals, 
although  not  classified  with  the  primary  forces  in  mechanics,  plays 
an  important  part  in  the  application  of  force  in  regulating  teeth. 
When  these  laws  and  their  applications  are  firmly  fixed  in  the  mind 
of  the  operator,  he  can  readily  take  advantage  of  the  one  which 
should  properly  be  applied,  or,  when  necessary  to  apply  more  than 
one,  can  combine  them  in  such  a  manner  as  will  best  accomplish 
the  desired  result. 

The  most  frequent  forms  of  irregularity  arc  protrusion  of  the 
cuspid  teeth,  misplaced  bicuspids,  contraction  of  the  arch,  protru- 
sion of  the  upper  jaw,  protrusion  of  the  lower  jaw,  torsion,  and  lack 
of  anterior  occlusion. 

434 


CORRECTION    OF   DENTAL    IRREGULARITIES.  4^ 

Protrusion  of  Cuspid  Teeth. — In  correcting  this  form  of  irreg- 
ularity, which  is  possibly  the  most  frequently  met  with,  we  have 
to  decide  from  other  existing  circumstances  whether  the  enlarge- 
ment of  the  arch  is  indicated  or  the  extraction  of  one  or  more 
teeth.  If  the  upper  arch  is  large  enough,  the  simple  extraction  of 
certain  teeth,  in  a  young  person,  will  allow  nature  to  correct  the 
deformity;  which  she  will  do  unaided  usually,  by  bringing  the  cus- 
pids down,  and  back  into  position.  In  extracting  teeth  for  regulating 
purposes,  a  mistake  is  frequently  made  in  the  selection  of  the  tooth 
or  teeth  to  be  removed ;  we  have,  in  our  practice  and  clinical  experi- 
ence, met  with  several  cases  where  practitioners  have,  at  times,  ex- 
tracted the  lateral  incisors,  allowing  the  cuspids  to  come  forward  and 
down,  and  on  other  occasions  the  cuspids  have  been  removed.  The 
result,  in  each  case,  has  been  an  almost  hopeless  deformity.  The 
cuspid  teeth  brought  next  to  the  central  incisors  oftentimes  gives  the 
face  a  canine  expression,  while  if  the  cuspids  are  removed  the  coun- 
tenance is  robbed  of  that  prominence  near  the  angles  of  the  mouth 
which  is  very  necessary  to  harmonious  expression ;  in  fact  the  cus- 
pids contribute  more  than  any  of  the  teeth,  unless  it  is  the  central 
incisors,  to  the  beauty  of  the  mouth.  In  consideration  of  these 
facts  it  is  readily  seen  that  the  practice  of  removing  the  projecting 
teeth  is  most  injudicious. 

It  is  a  disputed  point  as  to  which  of  the  teeth,  posterior  to  the 
cuspids,  can  be  best  spared  from  the  mouth,  and  for  these  cases  no 
rule  could  be  universally  adopted.  One  must  be  guided  entirely 
by  the  circumstances  existing  in  each  individual  case.  For  in- 
stance, when  the  space  between  the  lateral  incisor  and  the  first 
bicuspid  is  equal  to,  or  more  than  one-half  the  width  of  the  crown 
of  the  cuspid,  and  all  the  teeth  are  sound,  the  second  bicuspid 
should  be  removed ;  when  there  is  practically  no  space,  or  less  than 
that  mentioned  between  these  teeth,  the  first  bicuspids  are  the  teeth 
to  be  extracted.  If,  however,  the  bicuspids  are  all  sound,  and  the 
first  molars  are  badly  broken  down  by  caries,  the  removal  of  the 
latter  would  be  indicated,  after  which  the  bicuspids  could  be  brought 
back  by  suitable  appliances. 

Numerous  forms  of  appliances  are  employed  in  correcting  an 
irregular  arrangement  of  the  teeth,  as  every  case  presents  its  own 
peculiarities.     Those  which,  in  the  experience  of  the  writer  and 


436 


MECHANICAL    DENTISTRY. 


others,  have  proven  most  simple  in  construction  and  effectual  in 
treatment,  will  be  described  in  detail. 

When  teeth  have  been  removed  for  the  correction  of  irregular 
cuspids,  and  it  is  desired  to  hurry  the  operation,  or  where  the  bone 
is  too  hard  to  permit  nature  to  move  the  tooth  sufficiently,  appliances 
such  as  are  illustrated  in  Figs.  223  and  224  are  usually  employed. 
The  first,  Fig.  223,  was  originally  described  by  Dr.  S.  H.  Guilford. 

A  platinum  band,  with  short  gold  wires  soldered  to  the  buccal 
and  lingual  surfaces,  is  cemented  to  the  tooth  to  be  moved,  while 
a  similar  one  is  attached  to  a  molar  or  other  anchor  tooth.  The 
wires  on  the  anterior  band  are  bent  forward,  and  those  on  the 
posterior   one   are    curved    backward.     Two    rubber    rings,    caught 

Fig.  223. 


over  the  gold  hooks,  connect  the  two  bands  and  yield  the  tractile 
power  required.  These  rubber  rings  can  be  removed  and  replaced 
for  cleansing  the  teeth,  or  can  be  renewed  at  will  by  the  patient. 
Two  rings  can  be  attached  to  each  pair  of  hooks,  if  greater  power 
be  required;  or  the  same  object  can  be  attained  by  cutting  wider 
rings  from  thicker  tubing. 

The  second  method,  introduced  by  Dr.  E.  H.  Angle,  and  illus- 
trated in  Fig.  224,  is  a  part  of  what  is  known  as  the  "  Angle  system 
of  regulating  " — one  of  the  best,  most  complete,  and  simplest  sys- 
tems extant. 

The  first  molar,  or,  when  considered  necessary,  two  teeth,  may 
be  encircled  by  a  metallic  band,  to  which  is  soldered  a  piece  of 
tubing  to  accommodate  the  traction  bar  or  screw.     A  band  is  also 


CORRECTION    OF    DENTAL    IRREGULARITIES. 


437 


fitted  to  the  cuspid ;  to  this  a  short  tube  is  soldered  on  the  palato- 
distal  portion,  into  which  the  bent  end  of  the  traction  screw-bar  is 


engaged.     The  nut,  which  is  operated  against  the  distal  end  of  the 
tube,  will  readily  move  the  tooth  into  position. 

We  sometimes  meet  with  obstinate  cuspid  teeth,  which  refuse  to 
drop  into  line  after  the  necessary  room  has  been  secured  for  them. 

Fig.  225. 


When  this  is  the  case,  an  appliance,  such  as  is  illustrated  in  Fig. 
225, — the  pull-back  jack-screw  devised  by  Dr.  F.  H.  Lee. — 
answers  the  purpose  admirably. 


43§ 


MECHANICAL    DENTISTRY. 


The  post  or  nut  shown  in  the  side  cut  is  set  in  position  and  held 
by  vulcanizing  into  a  rubber  plate  as  shown  in  the  illustration ; 
the  screw-bolt  is  then  placed  through  the  post  and  a  wire  is  passed 
around  the  tooth,  the  ends  being  secured  to  the  holes  in  the  cross- 
head  or  swivel-block.  The  wire  is  then  taken  up  and  tightened  as 
the  tooth  is  brought  into  place.  To  prevent  the  plate  from  being 
moved  out  of  position  by  the  strain  upon  it,  it  should  be  secured 
to  the  teeth  of  the  arch  by  ligatures. 

Correction  where  the  Cuspid  Tooth  is  Inside  the  Arch. 
— The  power  usually  necessary  to  move  an  inlying  cuspid  is  very 
great.  The  jack-screw  is,  therefore,  one  of  the  forms  of  appli- 
ances; this,  however,  may  sometimes  be  aided  by  what  is  known 
as  the  inclined  plane.     Dr.  Angle's  method  is  shown  in  Fig.  226. 


Fig.  226. 


Fig.  22j. 


The  base  of  the  tube  containing  the  screw-liar,  or  jack-screw,  is 
soldered  to  a  band  encircling  the  opposite  cuspid  and  reinforced 
by  a  spur  resting  against  the  first  bicuspid  (see  illustration),  and 
also  by  the  large  traction  screw,  which  is  hooked  into  a  pipe 
soldered  to  the  labial  surface  of  the  band  and  passing  in  front  of 
the  incisors  through  a  tube  soldered  to  a  band  on  the  labial  surface  of 
the  incisors,  against  which  the  nut  works.  In  this  case,  the  left 
central  and  lateral  were  moved  forward  in  the  line  of  the  arch, 
thereby  closing  the  space  between  the  centrals,  and,  at  the  same 
time,  providing  space  for  the  out-moving  cuspid.  The  large  screw 
was  beaten  flat  and  polished  before  insertion. 

The   Inclined  Plane. — One  of  the   earliest  methods   employed 
in  correcting,  or  aiding  to  do  so,  where  the  superior  cuspid  or  in- 


CORRECTION    OF   DENTAL    IRREGULARITIES. 


439 


cisor  teeth  were  interlocked,  was  what  is  known  as  the  inclined 
plane.  This  is  formed  of  metal,  by  first  striking  up  a  saddle  to 
cover  two  or  more  of  the  lower  incisors.  To  this,  at  the  desired 
point,  is  soldered  an  inclined  piece  of  heavy  metal,  so  directed  that 
when  the  appliance  is  cemented  in  position  the  inlocked  tooth  will 
strike  upon  it  in  mastication  and  be  forced  outward  into  line.  Fig. 
227  shows  a  form  of  this  appliance. 

Fig.  228. 


No,  2 


No.  1. 


Another  device  for  the  same  purpose  is  that  of  Dr.  T.  Stanton 
Holmes,  wherein  is  combined  the  screw  and  spring  methods.  Fig. 
228  shows  the  appliance  in  position.  It  is  operated  by  the  nut-fitting 
ends  of  the  wrench ;  the  turning  of  the  screw  causes  a  forceful 
spring  action  to  the  extent  only  of  the  screw  thrust,  and  so  avoids 
the  common  danger  of  spring  action,  which,  if  neglected,  may  carry 


44Q 


MECHANICAL   DENTISTRY. 


the  tooth  too  far.  The  screw  is  made  by  the  substitution  of  a  long 
head  No.  2,  for  the  short  head  of  No.  1. 

Misplaced  Bicuspids. — A  simple  method  of  moving  bicuspids 
into  position  when  they  are  inside  the  arch  is  the  simple  jack- 
screw  of  the  Angle  system.  Another  very  ingenious  method  is  the 
Jackson  crib  and  spring  appliance.*  Fig.  229  shows  such  an  appli- 
ance in  position.  A  base  wire  is  shaped  to  the  lingual  side  of  the 
anterior  teeth  and  anchored  to  the  bicuspids  by  means  of  a  single 
"  crib  "  appliance.  To  each  of  these  latter  is  attached  a  hook  or 
eyelet  to  sustain  a  straight  bar  of  spring  wire  that  is  sprung  over 
the  anterior  teeth. 

Dr.  Jackson  gives  another  very  simple  fixture  for  the  purpose  of 


Fig.  229. 


Fig.  230. 


moving  a  single  bicuspid  either  inward  or  outward.  It  is  shown 
in  Fig.  230. 

A  spring  wire  is  bent  in  the  form  of  a  crib  surrounding  the  mis- 
placed tooth  and  an  adjoining  one  on  each  side,  passing  well  up 
toward  the  gum  on  the  labial  and  lingual  sides,  with  the  ends  of 
the  spring  wire  terminating  and  overlapping  upon  the  tooth  to  be 
moved.  The  elasticity  of  the  spring  will  exert  enough  force  to 
move  the  tooth. 

Contraction  of  the  Arch. — The  enlargement  of  the  arch  by 
lateral  expansion  may  be  accomplished  by  a  number  of  methods. 
Older  practitioners  usually  make  use  of  the  Coffin  split  plate,  but 


*  Devised  by  Dr.  V.   H.  Jackson,  of  New  York. 


CORRECTION    OF   DENTAL   IRREGULARITIES. 


441 


it  is  the  author's  opinion  that  heavy,  cumbersome  appliances 
should  be  discarded  as  far  as  possible.  Among'  the  neatest  and 
most  effective  for  this  purpose  are  those  devised  by  Dr.  Eugene 
Talbot  and  Dr.  Angle.     Dr.  Talbot's  method  is  as  follows : 

A  vulcanite  plate  is  made  to  fit  the  teeth  and  alveolar  process, 
and  cut  away  so  that  the  anterior  parts  extend  far  enough  forward 
to  inclose  the  teeth  to  be  moved.  (See  Fig.  231.)  A  piece  of  piano- 
wire  is  bent  into  either  of  the  forms  shown  in  Fig.  232,  wherein  a 
is  the  coil  and  fixed  point ;  b  b,  movable  arms  extending  from  a, 
and  c  c,  movable  arms  extending  from  b  b.  Grooves  are  cut  into 
the  anterior  and  posterior  parts  of  the  plate  to  correspond  with  and 
receive  the  points  b  b  and  c  c.     Holes  are  drilled  at  these  points, 


Fig.  231. 


and  the  wires  tied  to  the  rubber  plates.  In  order  that  the  anterior 
teeth  may  be  moved  with  the  greatest  force,  the  arms  are  so  ad- 
justed that  the  greatest  pressure  is  exerted  on  the  anterior  parts  of 
the  plate.  This  appliance  is  readily  removed  for  cleansing  and 
returned  to  place  by  the  patient. 

Dr.  Angle's  method  utilizes  the  principle  of  the  Coffin  spring 
without  the  objectionable  features  of  the  rubber  plate.  It  can  be 
used  either  in  the  upper  or  lower  arch ;  and  where  no  greater  power 
than  the  spring  affords  is  needed  will  prove  very  efficient.  As  seen 
in  Fig.  233  a  rubber  ligature  may  be  attached  to  the  center  of  the 
spring  and  be  connected  with  any  cross-bar  appliance  upon  the 
incisors  for  drawing  them  inward  when  such  additional  movement 
is  desired. 


442 


MECHANICAL   DENTISTRY. 


A  very  excellent  method  of  spreading  the  arch  is  that  practised 
by  Dr.  C.  Heydenhauss,  Dentist  to  the  Court  of  H.  R.  M.,  the 
Grand  Duke  of  Sachsen-Weimar. 

In   a  recent  interview  with  Dr.   Heydenhauss,   he   explained  his 

Fig.  233. 


methods  to  the  editor  as  given  below.  The  Doctor  has  made  use 
of  the  continuous  gold-caps  in  this  work,  as  illustrated  in  Figs.  234- 
237,  for  several  years,  and  presented  the  same  to  the  Odontological 
Society  of  Geneva,  Switzerland.  It  consists,  first,  of  capping  the 
teeth    on    both    sides    of    the    mouth,    from    the    cuspids    back    to 

Fig.  234. 


^  WMMWMMMWm 


the  second  molars,  with  continuous  shell-crowns.  These  crowns 
are  constructed  of  one  continuous  piece  of  gold  plate,  22-carat. 
The  cuspid  teeth,  however,  if  they  are  to  be  forced  outward, 
only  need  covering  on  the  palatine  surface.  This  is  all  clearly 
shown   in   Fig.    234.     After    the    crowns    are    well    fitted    and    fin- 


CORRECTION    OF   DENTAL    IRREGULARITIES. 


443 


ished,  two  platinized  gold  bars  are  soldered  to  their  palatal  surface 
and  shaped  according  to  the  form  of  the  palatine  vault.  To 
one  side  a  heavy  screw-bar  is  soldered,  while  to  the  other  a  short 
hollow  tube,  to  receive  the  free  end  of  the  screw-bar,  is  attached. 
The  screw-bar  is  provided  with  a  nut,  which,  after  the  crowns 
have  been  securely  set  with  cement,  is  turned  up  on  the  bar  until 
moderate  pressure  is  exerted.  This  nut  is  then  given  two  or  three 
turns,  three  or  four  times  a  week,  according  to  the  case  in  hand. 
The  appliance  in  position  is  shown  in  Fig.  235. 

When  it  is   desirable   to   expand   the   lower   maxilla,   continuous 
•crowns  are  made  as  has  been  directed,  but  to  each  of  these  an  open 

Fig.  235. 


'Cylinder  is  soldered  to  the  lingual  surface.  This  is  done  by  fit- 
ting and  soldering  a  gold  tube  over  a  piece  of  piano-wire  of  the 
same  size  as  the  wire  which  is  to  exercise  the  traction.  After  this 
is  done,  the  gold  tube  is  cut  in  its  long  axis,  by  which  we  get  the 
open  cylinders.  The  posterior  ends  of  these  tubes  are  closed  so 
as  to  receive  the  ends  of  the  traction  wire  when  in  position.  When 
the  crowns  are  secured  in  position  with  cement,  a  piece  of  piano- 
wire,  previously  shaped  from  the  cast  or  die,  is  sprung  into  the  open 
tubes.  To  exercise  the  necessary  traction,  the  wire  must  be  slightly 
spread  before  placing  it  in  the  mouth. 

The  placing  of  this  wire   requires   some   skill,   but  is,   however, 
easily   understood.     To    prevent    oxidation    the    wire    can    be    gold 


444 


MECHANICAL    DENTISTRY. 


plated.     The  wire   should  be  taken   out   every   two   or   three  days 
and  slightly  expanded,  then  replaced.     This  appliance  is  shown  in 


Figs.  236  and  237. 


Protrusion  of  the  Upper  Jaw. — One  of  the  most  efficient  meth- 
ods of  reduction  in  superior  protrusion  is  that  given  by  Dr.  Angle*. 

Fig.  236. 


It  consists  of  anchor  bands  (D,  Fig.  238)  for  the  molar  teeth,, 
with  long  tubes  soldered  to  their  buccal  surfaces  to  receive  the 
wire  bow-spring,  which  rests  in  front  in  notched  projections  upon 
the  bands  cemented  to  the  central  incisors.  At  the  center  of  the 
bow-spring  is  soldered  a  short  tube,  having  upon  its  labial  sur- 
face a  rounded  projection  to  receive  the  standard  (cupped  at  its  free 

Fig.  237. 


end)  of  the  long  traction  bar,  Fig.  239.  In  use,  the  clamp  bands 
(D)  are  attached  to  the  anchor  teeth,  and  the  plain  bands  (A,  A) 
cemented  to  the  central  incisors.  The  bow-spring  is  now  placed  in 
position. 

Occipital   resistance  is  obtained  by  means  of  a  netted  cap,   fas- 


CORRECTION    OF   DENTAL    IRREGULARITIES. 


445 


tened  to  a  circle  of  wire  fitted  to  the  head,  to  which  are  attached 
rubber  bands.  When  the  cupped  standard  of  the  traction  bar  has 
been  placed  over  the  central  spur  of  the  bow-spring,  the  rubber 
bands  of  the  cap  are  drawn  forward  and  looped  over  the  curved 
ends  of  the  traction  bar,  as  shown  in  Fig.  240.  This  cap,  traction 
bar,  and  rubber  bands,  are  worn  only  at  night,  on  account  of  their 

Fig.  238. 


conspicuousness.  During  the  day,  rubber  rings  (B,  Fig.  238)  are 
caught  over  the  tubes  on  the  molar  bands  and  secured  by  ligatures 
to  projections  on  the  bow-spring  in  the  region  of  the  cuspid  teeth. 
The  appliance  in  position,  as  worn  during  the  day,  is  illustrated  by 
Fig.  241. 

After  reduction  of  anterior  protrusion  we  are  met  with  the  diffi- 
culty of  retaining  the  results  gained.     Although  the  posterior  teeth 

Fig.  239. 


in  many  cases  will  not  furnish  the  resistance  necessary  for  drawing 
the  anterior  teeth  inward,  they  will  usually  answer  perfectly  for 
retaining  them  afterward.  Attachment  can  be  made  to  them  either 
by  means  of  a  rubber  plate  covering  the  roof  of  the  mouth  and 
extending  around  their  distal  surfaces  in  the  form  of  a  clasp,  or  by 
means  of  metal  bands  or  caps  cemented  to  them.     In  the  former 


446 


MECHANICAL   DENTISTRY. 


case,  a  small  round,  or  half  round,  gold  wire  may  be  made  to  pass 
around  the  arch,  touching  the  regulated  teeth  on  their  labial  sur- 


Fig.  240. 


Night  appliance. 

faces,  and  be  attached  at  each  end  to  the  rubber  plate  at  convenient 
points — as  where  teeth  have  been  extracted.     In  the  latter  case,  a 


similar  retaining  wire  may  be  soldered  to  the  molar  bands,  or  the 


CORRECTION    OF  DENTAL   IRREGULARITIES. 


447 


bands  may  have  tubes  soldered  to  their  buccal  surfaces  and  the 
wire,  threaded  at  the  extremities,  passed  through  these  and  re- 
tained by  means  of  nuts  operating  upon  them.  In  either  case,  the 
retaining  wire  should  have  short  gold  clips  attached  to  it  in  front 
to  engage  with  the  cutting  edges  of  at  least  two  of  the  incisor  teeth. 

When  it  is  desired  to  avoid  having  a  retaining  wire  pass  entirely 
around  the  front  of  the  arch,  a  rubber  retaining  plate  may  be  made 
with  a  gold  T  passing  between  the  centrals,  and  long  enough  to  rest 
upon  all  four  of  the  incisors.  Holding  these  teeth  firmly  in  place 
will  also  keep  the  cuspids  in  line  through  lateral  pressure. 

The  principal  appliances  of  the  Angle  system  are  manufactured 
and  kept  in  stock  at  the  dental  depots.  There  are  certain  portions, 
however,  which  have  to  be  united  or  soldered  to  suit  the  case  in 


Fig.  242. 


Fig.  243. 


hand,  and  as  these  fixtures  are  made  as  light  and  delicate  as  pos- 
sible, some  care  is  required  in  handling  them. 

In  uniting  the  parts  of  the  appliance  with  solder,  a  fine,  sharp 
flame  from  a  Bunsen  burner  is  most  desirable,  as  both  the  hands 
are  free  and  can  be  used  in  holding  the  pieces.  Notwithstanding 
many  ingenious  spring  clamps  and  devices  have  been  invented  for 
holding  such  small  work  while  soldering,  yet  the  method  of  hold- 
ing them  with  the  fingers  is  greatly  to  be  preferred,  as  it  is  much 
easier  and  simpler,  steadying  the  hands  by  touching  the  fingers 
together,  as  shown  in  Figs.  242  and  243. 

In  writing  of  this  subject,  Dr.  Angle  says: 

"The  small  tubes  are  best  held  by  slipping  them  on  to  the  end 
of  an  excavator  shank,  or,  what  is  just  the  ideal,  one  of  Gates' 


448  MECHANICAL   DENTISTRY. 

nerve  drills  after  the  cutting  point  has  been  broken  off.  It  is  so 
slender  that  but  little  of  the  heat  is  absorbed.  Two  of  these 
handles  may  be  employed  when  a  couple  of  the  small  tubes  are 
soldered,  or  the  pliers  may  be  used  for  holding  one  of  them.  (See 
Fig.  243.) 

"  I  should  judge  it  not  difficult  to  learn  this  method  of  soldering; 
the  only  point  which  at  all  may  perplex  the  beginner  is  to  hold  the 
pieces  immovable  just  at  the  time  solder  is  congealing,  but  this  can  be 
done  by  touching  the  fingers  of  the  opposite  hand  in  order  to  steady 
and  prevent  all  motion  at  the  point  of  union,  and  at  the  same  time 
holding  the  pieces  gently,  not  rigidly,  just  as  a  good  penman  holds 
a  pen.  After  a  little,  any  of  the  combinations  may  be  easily  made 
in  a  very  few  minutes.  Where  the  ends  of  small  tubes  are  to  be 
secured,  it  is  best  to  first  fuse  the  solder  upon  the  band,  and  then 
hold  the  small  tubes,  by  means  of  the  soldering  pliers,  in  con- 
tact with  the  solder  and  again  apply  heat,  otherwise  the  solder  will 
be  drawn  into  the  tube.  The  solder  best  adapted  in  uniting  the 
different  parts  of  these  appliances  is  the  ordinary  jeweler's  silver 
solder,  although  18-carat  gold  solder  may  be  used.  Plenty  of 
borax  should  always  be  used  as  a  flux.  Scrape  bright  the  silver 
solder  and  the  points  to  be  soldered,  and  borax  both.  Never  use 
more  solder  than  is  necessary,  especially  in  attaching  the  small 
tubes;  use  just  sufficient  to  make  the  union. 

"  Always  avoid  overheating;  just  enough  heat  from  a  small  flame 
to  thoroughly  fuse  the  solder  is  all  that  should  ever  be  employed. 
In  every  instance  avoid  heating  the  screws  or  nuts.  This  is  to  be 
especially  observed  with  the  jack  and  traction  screws,  as  great  care  is 
observed  in  their  manufacture  to  produce  the  greatest  stiffness  and 
strength,  and  this  fine  temper  is  ruined  by  heating." 

Protrusion  of  the  Lower  Jaw. — When  this  deformity  is  slight, 
it  may  usually  be  corrected  by  drawing  the  lower  incisors  in  and 
the  upper  ones  outward.  Where  the  case  is  a  pronounced  one, 
there  is  no  remedy  except  the  retraction  of  the  entire  lower  jaw. 
In  many  cases,  however,  the  two  measures  can  be  combined  to 
advantage. 

Method  of  Retraction. — It  was  for  many  years  supposed  that 
the  retraction  of  the  inferior  maxilla  was  brought  about  entirely 
by  a  change  effected  at  the  angle  of  the  jaw ;  but  some  years  ago 
it  was  noticed  by  Prof.  C.  N.  Peirce  that  where  sufficient  pressure 


CORRECTION    OF   DENTAL   IRREGULARITIES. 


449 


was  brought  to  bear  a  change  was  brought  about  in  the  temporo- 
maxillary  articulation.  That  is,  if  pressure  was  continued  at  the 
mental  region,  it  would  cause  resorption  of  the  posterior  wall  of 
the  glenoid  cavity,  thus  permitting  the  condyles  to  recede,  and  ar- 
ticulate somewhat  posteriorly  to  their  former  positions. 

Through  this  fact,  and  the  change  that  is  brought  about  at  the 
angle  of  the  jaw,  we  are  enabled  to  correct  one  of  the  most 
unsightly  of  dental  deformities.  The  method  of  procedure  is  well 
illustrated  by  a  case  brought  before  the  Odontological  Society  of 


Fig.  244. 


l 


New  York  by  Dr.  Geo.  S.  Allen.  He  says,  in  part :  "  As  will  be 
seen  from  the  photograph  (Fig.  244),  taken  at  the  time  the  patient 
was  wearing  this  apparatus,  it  consists  of  two  parts.  For  the  lower 
part  I  made  a  brass  plate  to  fit  the  chin,  having  arms  with  hooked 
ends  reaching  to  a  point  just  below  the  point  of  the  chin. 
These  arms  were  arranged  in  such  a  way  that  the  distance  between 
them  could  be  altered  at  will  by  simply  pressing  them  apart  or  to- 
gether. The  upper  part  consisted  of  a  simple  network,  going  over 
the  head  and  having  two  hooks  on  each  side,  one  hook  being 
above  and  the  other  below  the  ear.  When  this  apparatus  was 
29 


45° 


MECHANICAL   DENTISTRY. 


completed  and  in  use,  there  were  four  ligatures  of  ordinary  elastic 
rubber  pulling  in  such  a  way  as  to  force  the  lower  jaw  almost  di- 
rectly backward.  The  work  proceeded  very  rapidly,  so  that  at  the 
end  of  two  months  the  irregularity  was  almost  entirely  cured." 

A  very  good  method  of  making  the  chin  piece  is  that  described 
by  Dr.  Guilford.  Take  impression  of  the  chin  and  from  this  make 
a  model.  The  model  is  then  overlaid  with  a  piece  of  trial-plate 
wax,  from  which,  after  being  varnished,  a  mold  in  sand  is  obtained 
and  a  die  and  counter-die  made.  Between  these  a  piece  of  soft  and 
heavy  brass  plate  is  struck  up  and  drilled  full  of  holes.  After 
fashioning  heavy  piano  wires  to  cross  the  plate  and  extend  suffi- 
ciently beyond  to  form  hooks,  they  are  soft-soldered  to  the  brass 
plate  and  the  latter  covered  with  black  silk,  with  a  thick  layer  of 
cotton  batting  laid  between  the  two. 

The  enlarged  size  of  the  chin  piece  will  admit  of  this.     The  piece 

Fig.  245.  Fig.  246. 


thus  padded  will  fit  the  chin  and  be  soft  enough  to  prevent  pain 
when  pressure  is  brought  to  bear  upon  it. 

Torsion. — The  term  torsion,  when  applied  to  the  teeth,  sig- 
nifies that  condition  in  which  a  tooth  is  found  to  be  turned  upon  its 
axis.  Rotation  refers  to  the  act  of  turning  a  tooth  so  as  to  bring  it 
into  normal  position.  Torsion,  therefore,  describes  the  condition, 
while  rotation  refers  to  the  operation. 

Rotation  by  Rubber  Rings. — In  the  accompanying  illustra- 
tions, Figs.  245  and  246,  Dr.  Guilford's  method  of  employing  bands 
and  rubber  rings  for  rotation  is  given.  Platinum  bands  were  fitted 
to  the  centrals,  with  a  gold  hook  soldered  to  each  at  points  that  would 
furnish  the  greatest  amount  of  tractile  power.  After  the  bands 
were  cemented  in  place  a  rubber  ring  was  stretched  from  tooth  to 
tooth,  in  the  manner  shown  in  Fig.  245.  The  malposed  tooth  was 
thus  readily  brought  into  contact  with  its  fellow,  and  at  the  same 
time  considerably  straightened.  After  which  it  was  retained  by 
the  retainer  shown  in  Fig.  246. 


CORRECTION    OF   DENTAL    IRREGULARITIES.  45 1 

Rotation  by  Spring  Bar. — When  the  mesial  angles  protrude, 
double  rotation  can  be  accomplished  by  the  very  simple  and  effec- 
tual method  recommended  by  Dr.  Angle. 

Upon  each  of  the  teeth  to  be  rotated  place  bands  with  tubes  sol- 
dered to  their  labial  faces  near  the  distal  angles.  One  tube  is  set 
vertically  and  the  other  horizontally.  A  soft  piece  of  piano  or 
German  silver  wire,  bent  to  a  right  angle  at  one  end,  is  inserted  in 
these  tubes,  and  rotation  is  effected  by  the  elasticity  of  the  wire  (Fig. 
247).  Once  in  position,  the  teeth  are  retained  by  inserting  in  the 
tubes  a  suitably  shaped  piece  of  non-elastic  gold  wire,  as  shown  in 
Fig.  248. 

Lack  of  Anterior  Occlusion. — This  form  of  irregularity  is  for- 
tunately rare,  as  it  is  one  of  the  least  amenable  to  treatment.  The 
cause  is  usually  the  lack  of  alveolar  development  in  the  anterior 
portion  of  the  mouth,  sometimes  accompanied  with  an  excessive 
growth  in  the  molar  region. 

Fig.  247.  Fig.  248. 


Treatment. — When  the  deformity  is  slight  it  may  be  corrected 
by  grinding  off  all  the  antagonizing  points  from  the  posterior  teeth, 
which  will  shorten  the  bite,  bringing  the  anterior  teeth  closer  to- 
gether. If  the  third  molars  were  in  position  and  adding  to  the 
trouble  they  should  be  extracted.  Then,  if  necessary,  one  or  more 
of  the  remaining  molar  teeth  upon  either  side  of  the  mouth  (those 
in  the  poorest  condition  to  be  selected)  may  be  devitalized,  ground 
down  beyond  the  point  necessary,  and  then  covered  with  gold 
crowns. 

Where  considerable  grinding  upon  vital  teeth  is  done  and  the 
exposed  dentine  becomes  quite  sensitive,  it  may  be  obtunded  by  a 
repeated  application  of  either  chlorid  of  zinc  or  nitrate  of  silver. 

Unusual  Forms  of  Irregularities. — The  following  cases  of  un- 
usual forms  of  irregularities,  illustrated  in  Figs.  249,  250,  251,  and 
252,  were  treated  and  described  by  Dr.  Angle.  The  first,  Fig.  249, 
shows  the  manner  of  bringing  a  cuspid  tooth  out  into  line,  that  is, 


452 


MECHANICAL   DENTISTRY. 


aiding  it  to  erupt.  The  clamp  band  was  fixed  on  the  lower  second 
bicuspid.  A  very  small  hole  was  drilled  into  the  cuspid,  and  a 
short  pin  was  set  with  thin  cement.  A  common  pin  answers  the 
purpose,  and  the  hole  need  not  be  deeper  than  the  enamel  if  the 
pin  is  accurately  fitted  to  it.  A  rubber  ligature  was  given  the 
patient,  with  instructions  to  slip  it  over  the  pins,  as  shown  in  the 

Fig.  249. 


engraving.  The  anchor  tooth  in  this  case  is  directly  opposed  by 
the  superior  bicuspid.  The  anchorage  is  simple  and  efficient. 
The  ligature  may  be  worn  at  night  only,  so  as  to  interfere  as  little 
as  possible  with  speech  and  mastication,  although  some  patients  wear 
it  almost  continuously.  Too  strong  a  ligature  should  not  be  worn, 
as  it  might  endanger  the  life  of  the  pulp,  but  gentle  traction  should 
be  used,    gradually    directing   the    tooth   into    its    proper    position. 

Fig.  250. 


The  direction  of  force  to  be  exerted  upon  the  tooth  to  be  moved 
will,  of  course,  indicate  which  tooth  in  the  inferior  arch  should  be 
selected  for  anchorage.  Should  the  anchorage  fall  upon  a  tooth 
with  no  antagonist  there  would,  of  course,  be  danger  of  loosen- 
ing it. 

Fig.  250  shows  a  case  in  which  the  anchorage  was  modified  to 
suit   the   conditions.     A   deciduous   cuspid   had  been   retained   too 


CORRECTION    OF   DENTAL    IRREGULARITIES. 


453 


long,  causing  the  permanent  cuspid  to  remain  in  the  alveolar 
process  on  the  palatal  side  of  the  lateral  incisor,  necessitating  a 
complex  movement  of  the  tooth  backward,  outward,  and  down- 
ward, requiring  a  very  firm  anchorage  and  a  strong  ligature.  On 
the  inferior  cuspid  and-  second  bicuspid  were  fixed  bands,  having 

Fig.  251. 


pipes  attached  to  their  labial  surfaces.  A  piece  of  the  wire  of  suit- 
able length  was  bent  at  right  angles  and  hooked  into  the  pipes,  as 
shown.  The  wire  fits  the  bore  of  the  pipe  so  accurately  that  in 
cutting  off  the  ends  which  emerge  through  them,  each  end  spreads 
sufficiently  to  prevent  its  coming  out.     A  pin  was  soldered  to  the 

Fig.  252. 


wire  about  midway  between  the  pipes.     The  ligature  was  stretched 
from  pin  to  pin,  as  seen  in  the  engraving. 

Fig.  251  shows  a  modification  of  this  method  of  anchorage.  The 
anchor  wire  was  made  detachable  and  the  pin  dispensed  with,  the 
patient  slipping  the  wire  through  the  ligature  and  into  the  pipes 
upon  retiring,  and  removing  it  during  the  day.  A  delicate  band, 
to  which  was  soldered  the  pin,  was  fixed  on  the  moving  tooth. 


454 


MECHANICAL    DENTISTRY. 


Fig.  252  illustrates  a  case  in  which  the  appliances  used  were 
similar  to  those  before  described,  but  the  wire  anchorage  was  at- 
tached to  teeth  in  the  same  arch  in  which  was  located  the  malposed 
tooth.  The  first  bicuspid  was  banded  and  a  pipe  soldered  to  the 
labial  surface  of  the  band,  in  which  was  hooked  a  piece  of  the  wire, 
the  other  end  of  the  wire  being  bent  so  as  to  rest  on  the  cutting 
edge  of  the  lateral  incisor.  A  pin  was  soldered  to  this  wire,  as  in 
the  case  before  described,  and  a  rubber  ligature  stretched  from  pin 
to  pin. 

Regulating  Supplemented  by  Crown-work. — An  interesting 
case  treated,  and  reported  in  the  Dental  Cosmos,  by  Dr.  F.  M. 
Willis,  is  that  of  a  young  lady  who,  several  years  previous  to 
treatment,  had  the  left  superior  lateral  incisor  and  right  first  bi- 

Fig.  253. 


cuspid  extracted  by  a  dentist  to  correct  a  slight  irregularity.  The 
result  was  that  instead  of  remedying  the  condition,  there  was  a 
general  settling  in  of  the  entire  upper  jaw,  resulting  in  a  much 
worse  condition  than  the  first.  The  right  superior  central  incisor 
was  the  only  one  of  the  upper  teeth  that  touched  the  lower.  There 
was  a  space  of  *4  °f  an  mcn  between  the  upper  and  lower  bicuspids 
and  molars  when  her  jaws  were  brought  together.     (See  Fig.  253.) 

The  patient  was  unable  to  masticate  her  food  properly,  and  as  a 
natural  consequence  she  was  suffering  from  indigestion  so  badly 
that  she  was  unable  to  attend  school,  and  her  system  was  very  much 
run  down. 

A  split  plate,  with  a  piano  wire  spring,  was  made  to  spread  the 
upper  bicuspids  and  molars.     The  patient  wore  this  appliance  for 


CORRECTION    OF   DENTAL    IRREGULARITIES.  455 

six  weeks,  calling  once  a  week  to  have  the  spring  opened  as  the 
case  progressed.  The  upper  molars  and  bicuspids  were  now  di- 
rectly over  the  corresponding  teeth  of  the  lower  jaw,  having  been 
spread  about  34  oi  an  inch. 

The  cuspids  occupied  about  the  right  position,  so  the  next  step 
was  to  move  forward  the  centrals  and  lateral  incisor.  A  gold  band 
was  fitted  around  the  right  central,  with  a  spud  resting  behind  the 
other  central  and  the  lateral  incisor.  The  left  central  and  the  lateral 
incisor  were  somewhat  twisted  on  their  axes,  so  the  spuds  resting 
behind  them  were  bent  so  as  to  twist  these  teeth  as  they  moved 
forward.  A  plate  was  made,  covering  the  molars  and  bicuspids, 
with  a  piano  wire  spring  resting  in  a  notch  in  the  gold  band 
behind  the  right  central.  This  appliance  was  worn  for  a  month. 
The  incisors  were  now  straight  on  their  axes,  and  were  far 
enough  forward  to  allow  them  to  shut  outside  the  lower  teeth. 
Now  when  her  jaws  were  closed  there  was  less  than  -Jg  of  an  inch 
space  between  the  bicuspids  and  molars  of  the  upper  and  lower 
jaws. 

The  lower  molars  and  bicuspids  were  badly  broken  down  from 
decay,  some  of  them  having  been  filled  half  a  dozen  times.  To 
put  them  in  good  condition  and  raise  their  grinding  surfaces 
to  articulate  with  the  upper  teeth,  it  was  decided  to  crown  them 
with  gold.  The  molars  were  capped  in  the  usual  way  with  gold 
crowns. 

In  order  to  avoid  too  much  show  of  gold  on  the  bicuspids, 
a  new  method  was  resorted  to  in  crowning  them.  A  gold  band 
was  fitted  around  the  tooth,  extending  about  Jg  of  an  inch  above 
the  end  of  the  tooth.  An  impression  and  bite  were  taken  at  the 
same  time  by  covering  the  tooth  and  band  with  plaster  and  closing 
the  jaws  while  the  plaster  was  soft.  The  band  and  plaster  were 
removed  intact,  and  Melotte's  fusible  metal  poured  into  the  band 
and  a  pin  stuck  into  the  metal  to  hold  in  the  plaster.  The  crown 
was  placed  on  the  articulator,  and  the  bite  completed  with  Melotte's 
metal  and  plaster.  The  plaster  was  now  removed  from  the  band, 
leaving  a  metallic  surface  Jg  of  an  inch  below  the  top  of  the  band, 
against  which  to  fit  a  porcelain  top  for  the  crown.  In  this  case 
an  ordinary  plain  tooth,  such  as  is  used  in  vulcanite  work,  was 
selected  and  ground  to  fit  into  the  gold  band  and  the  right  length 
to  articulate  with  the  upper  teeth.     This  porcelain  tip  was  cemented 


456 


MECHANICAL    DENTISTRY. 


into  the  gold  band,  and  the  whole  removed  from  the  articulator. 
The  fusible  metal  was  heated  a  little,  and  readily  came  away  from 
the  crown.     Fig.  254  represents  the  finished  crown. 

These  crowns  were  cemented  on  in  the  mouth  and  produced  a 
nice  appearance,  as  nothing  but  the  porcelain  showed  when  the 
mouth   was  opened,   the   lip   and  tongue   entirely   hiding   the   gold 

Fig.  255. 


A.  Porce- 
lain tip. 
B.  Gold 
band. 


band.  A  crown  of  this  description  is  particularly  advantageous 
for  the  lower  molars  and  bicuspids,  especially  where  they  need  to 
be  brought  up  some  distance  above  the  natural  tooth. 

Such  a  crown  can  be  made,  with  absolute  accuracy,  in  one 
hour,  and  there  is  no  risk  of  a  fractured  porcelain,  as  no  heat 
is  used. 

Fig.  255  represents  the  case  completed. 

Reposing  the  Features  in  Orthodontia. — The  science  of  ortho- 
dontia, under  the  influence  of  modern  methods  of  practice  and 
improved  appliances,  is  now  claiming  a  distinct  field  in  dental  art 
and  mechanics,  embracing  the  esthetic  contours  of  the  face  as 
well  as  the  movement  and  rearrangement  of  individual  teeth.  In 
the  ordinary  practice  of  this  branch  of  dentistry,  not  enough  atten- 
tion has  been  given  to  facial  effects;  the  aim  usually  being  simply 
to  bring  the  teeth  to  a  more  perfect  occlusion,  with  little  regard 
to  the  movement  of  the  roots,  and  the  surrounding  bony  struc- 
ture. In  examining  dental  literature,  little  is  found  in  regard  to  the 
movement  of  roots,  and  methods  by  which  it  may  be  accomplished; 
and  it  was  not  until  Dr.  Calvin  S.  Case  presented  his  paper  at  the 
World's  Columbian  Dental  Congress  that  much  of  practical  value 
in  the  development  of  esthetic  facial  contours  was  established. 


CORRECTION    OF   DENTAL    IRREGULARITIES. 


457 


To  illustrate  the  possibilities  in  the  treatment  of  dental  irregu- 
larities, we  present  an  interesting  case  from  among  those  we  have 
recently  treated.  It  is  that  of  a  young  man  of  eighteen,  whose 
mouth  presented  a  very  homely  appearance.  The  upper  jaw  was 
contracted  upon  the  sides  and  very  prominent  in  front,  with  very 
large,  protruding  incisors  and  cuspid  teeth.  The  median  line  of 
the  face,  too,  was  nearly  the  width  of  a  central  tooth  to  the  left, 
giving  the  jaw  a  twisted  appearance,  as  though  the  teeth  had  been 
forced  over  in  a  body  to  the  right.  Fig.  256  gives  a  fair  idea  of 
the  appearance  of  the  mouth  when  the  work  was  commenced.  A 
bicuspid  was  extracted  upon  either  side.  The  left  cuspid  was  then 
drawn  back  to  the  position  formerly  occupied  by  the  first  bicuspid 

Fig.  256. 


by  an  appliance  similar  to  that  illustrated  in  Fig.  223,  page  436 ; 
then  the  lateral  incisor  was  brought  over  to  the  left,  which  was 
followed  by  the  centrals ;  in  this  way  the  center  of  the  teeth  was 
brought  nearly  to  the  median  line  of  the  face.  The  next  procedure 
was  to  band  the  molars  and  bicuspids  upon  either  side,  upon  the 
buccal  surface  of  which  a  hook  was  soldered,  directed  backward;  a 
gold  cap  was  then  made  with  hooks  directed  forward,  and  cemented 
upon  the  central  incisors.  Rubber  bands  were  then  brought  from 
the  posterior  hooks  to  those  in  the  front  of  the  mouth.  Very  light 
bands  were  employed  at  first,  which  were  gradually  increased  in 
width  and  strength  as  the  teeth  moved  inward  and  backward. 
While  this  was  being  done  a  light  jack-screw  (of  the  Angle  system) 
was  worn  in  the  mouth,  bringing  pressure  upon  the  second  bicus- 


458 


MECHANICAL    DENTISTRY. 


pids  and  molars,  which  gradually  enlarged  the  arch,  helping 
to  fill  out  the  face  upon  the  sides  and  giving  the  anterior  teeth 
more  of  an  opportunity  to  move  backward.  After  the  anterior 
teeth  were  drawn  back  as  near  to  the  normal  position  as  we  could 
bring  them,  the  pressure  was  relaxed  by  substituting  much  lighter 
bands,  which,  with  the  jack-screw  across  the  palate,  were  worn  for 
several  months.  When  these  fixtures  had  been  removed,  the  lat- 
eral incisors,  which  were  turned  slightly  upon  their  axes,  were 
rotated  by  the  means  of  ligatures,  and  a  gold  cap,  covering  the 
lower  half  of  the  six  anterior  teeth,  was  made  and  cemented  in 
position.  This  was  worn  as  a  retaining  appliance  for  six  months. 
The  results,  which  were  most  gratifying,  may  be  seen  by  compar- 
ing Figs.  256  and  257.  One  of  the  most  interesting  points  in  rela- 
tion to  this  case  is  that  the  work  was  completed  without  destroying 

Fig.  257. 


the  vitality  of  any  of  the  teeth,  which  is  too  often  the  case  where 
heavy,  cumbersome  appliances  are  employed  and  the  teeth  moved 
too  rapidly.  While  the  retaining  appliances  were  being  worn,  the 
third  molars  were  erupted  as  can  be  seen  by  referring  to  the  illus- 
trations. 

Dr.  Case's  Methods. — From  the  paper  referred  to  above  we 
have  selected  three  of  the  most  interesting  and  pronounced  cases. 
In  this  connection  Dr.  Case  states  that  he  is  now  able  to  correct, 
with  perfect  certainty  of  success,  any  marked  depression  or  pro- 
trusion of  the  upper  lip  which  is  mainly  due  to  a  malposition  of 
the  roots  of  the  incisor  teeth ;  and  further  says : 

"  Instances  are  often  observed  among  the  youth  who  demand  our 
professional  services  which  show  a  comparatively  perfect  alignment 
and  occlusion  of  the  teeth,  and  yet  because  of  the  position  of  the 


CORRECTION    OF   DENTAL    IRREGULARITIES.  459 

roots,  with  a  consequent  abnormal  depression  or  protrusion  of  the 
adjoining  bone,  considerable  imperfection  of  features  and  external 
contour  of  the  face  is  produced.  These  deformities  are  peculiar 
and  not  common,  but  have  rarely  engaged  attention  with  a  view 
of  orthopedic  treatment  directed  to  the  development  of  a  more 
esthetic  facial  form.  In  the  instance  of  a  marked  depression  of 
the  upper  lip,  as  in  Cases  I  and  2,  they  are  often  mistaken  for  a 
prognathous  lower  jaw,  because  of  the  lack  of  proper  fullness  in  the 
central  features  of  the  face,  which  frequently  affects  the  shape  of 
the  nose  and  deepens  the  lines  on  either  side.  For  the  same  reason 
the  cheek  bones  will  at  times  appear  abnormally  prominent,  giving 
to  the  face  a  broad  and  flattened  appearance,  especially  if  the  cus- 
pids, being  retarded  in  their  eruption  for  the  want  of  room,  take  a 
more  lateral  and  prominent  position.  If  the  lower  teeth  are  in 
proper  relative  position  and  the  deformity  caused,  as  is  most  com- 
mon, by  the  lower  incisors  occluding  in  front  of  the  upper,  every 
change  desirable  may  be  effected  by  an  appliance  attached  to  the 
superior  teeth  alone.  As  an  illustration  of  this,  I  call  attention 
to  the  models  in  Case  2. 

"  On  the  other  hand,  if  the  entire  superior  dental  arch  is  narrow 
and  contracted,  with  a  high  palatal  dome,  the  teeth  long,  uncrowded, 
and  not  materially  affected  in  position  by  occlusion,  the  face  will 
usually  be  long  and  narrow,  the  nose  prominent,  thin,  and  of  the 
Roman  type  (see  Fig.  264,  Case  1).  In  these  cases  the  entire 
dental  arch  and  alveolus  should  be  expanded,  and  the  force  so  ap- 
plied and  controlled  as  to  retain  the  teeth  in  an  upright  position, 
especially  in  the  process  of  carrying  the  anterior  teeth  forward, 
which  is  of  vital  importance  in  the  restoration  of  the  features  of  the 
face.  The  principal  force,  therefore,  should  be  exerted  upon  the 
anterior  superior  teeth ;  and  this  force  may  be  reciprocated  by  rub- 
ber bands  extending  from  the  posterior  part  of  the  upper  appliance 
to  the  anterior  part  of  an  appliance  that  is  attached  firmly  to  all  the 
lower  teeth.  These  bands  can  be  made  to  exert  almost  any  desired 
force,  according  to  the  heft  of  the  tubing  from  which  they  are  cut; 
and  their  positions  being  such  as  not  to  interfere  with  mastication, 
they  can  be  worn  continuously. 

"  If  the  inferior  dental  arch  is  large,  with  the  teeth  occluding 
outside  of  the  alignment  of  the  superiors,  it  may  be  reduced  in 


460  MECHANICAL   DENTISTRY. 

size  by  the  extraction  of  a  bicuspid  on  either  side  and  the  anterior 
teeth  forced  back  to  fill  the  space  (see  Case  1,  Figs.  264  and  265). 
If,  however,  the  chin  is  abnormally  prominent  below  the  incisive 
fossa?,  teeth  should  not  be  extracted  from  the  lower  jaw,  the  prin- 
cipal change  to  correct  the  facial  deformity  should  be  accomplished 
on  the  upper  jaw. 

"  I  have  abandoned  all  attempts  after  early  childhood  to  reduce  a 
prognathous  lower  jaw  by  external  pressure  upon  the  chin,  never 
having  derived  the  same  satisfaction  from  this  operation  that  others 
claim.  I  find,  however,  that  the  rubber  bands  before  mentioned, 
extending  from  the  upper  to  the  lower  appliance,  can  be  made  to 
exert  all  the  force  the  patient  can  stand  at  the  glenoid  fossse,  and 
doubtless  this  influence  tends  to  force  the  lower  jaw  to  a  more 
posterior  position.  Examples  of  deformities  of  this  character  and 
their  treatment  are  shown  by  Cases  I  and  2,  which  were  selected 
for  the  purpose  of  showing  the  varieties  of  protruding  lower  jaw 
and  teeth. 

"  On  the  other  hand,  with  equal  facility,  I  am  able  now  to  reduce 
a  protrusion  of  the  upper  lip  at  that  point  where  it  merges  into  the 
nasal  septum  and  orifices,  when  due  to  a  malposition  of  the  roots 
of  incisor  teeth  alone,  causing  an  abnormal  prominence  of  the  ante- 
rior nasal  spine  and  incisive  fossse.  (See  Case  3.)  This  position 
of  the  roots  of  the  superior  incisors  is  not  uncommon,  even  when 
the  antagonizing  ends  are  in  perfect  position ;  and  often  with  the 
production  of  quite  a  marked  facial  deformity. 

"  In  like  manner  I  am  able  to  force  the  anterior  inferior  teeth 
bodily  forward,  with  the  entire  alveolar  ridge  in  which  they  are  im- 
bedded. Instances  are  not  rare  where  the  point  of  the  chin,  the 
upper  lip,  and  the  anterior  superior  teeth  are  relatively  in  proper 
position,  but  with  inferior  teeth,  from  various  causes,  so  posteriorly 
placed  as  to  produce  an  abnormally  deep  depression  or  curve  in 
that  portion  of  the  lower  lip  along  the  line  of  the  incisive  fossse. 
By  forcing  the  anterior  inferior  teeth  forward,  with  the  alveolus  in 
which  they  are  imbedded,  a  more  esthetic  shape  will  be  given  to 
the  chin ;  and  this  change,  though  slight  according  to  measure- 
ment, will  often  produce  an  improvement  in  the  general  appearance 
of  the  face  that  is  quite  remarkable.  The  same  is  true,  also,  in  a 
posterior  movement  of  the  inferior  incisor  teeth  and  alveolus,  when 


CORRECTION    OF  DENTAL   IRREGULARITIES.  46 1 

they  are  so  anteriorly  placed  in  relation  to  the  point  of  the  chin  as 
to  obliterate  the  graceful  curve  of  the  lower  lip.  This  is  shown  in 
Case  1. 

;Ji  ^  >t<  ^  >i=  -'fi  $<  ;K  $'  H"  ^ 

"  Before  describing  the  peculiar  construction  of  the  contouring 
apparatus  I  use  in  these  cases,  I  wish  to  say  that  I  endeavor  to 
have  all  regulating  appliances  made  as  substantially  and  finished  as 
perfectly  as  a  piece  of  jewelry.  The  bands  are  fitted  to  the  natural 
teeth  with  as  much  perfection — especially  where  they  extend  under 
the  free  margins  of  the  gum — as  a  band  for  a  crown.  I  use  German 
silver  principally,  and  heavily  gold-plate  the  apparatus  before 
attachment. 

"  The  limited  area  upon  which  force  can  be  applied  to  a  tooth, 
compared  to  that  portion  covered  by  the  gum  and  imbedded  in  a 
hony  socket,  has  made  it  next  to  impossible,  with  all  ordinary 
methods,  to  move  the  apex  of  the  root  in  the  direction  of  the 
applied  force;  nor  could  this  ever  be  accomplished  with  force 
exerted  in  the  usual  way  at  one  point  upon  the  crown,  however 
near  the  margin  of  the  gum  it  be  applied,  for  the  opposing  margin 
■of  the  alveolar  socket  must  receive  the  magnitude  of  this  direct 
force,  and  in  proportion  to  its  resistance  it  will  become  a  fulcrum 
exerting  a  tendency  to  move  the  apex  of  the  root  in  the  opposite 
direction. 

"  But  if,  in  the  construction  of  the  apparatus,  a  static  fulcrum  is 
created  independent  of  the  alveolus  at  a  point  near  the  occluding 
portion  of  the  crown,  while  the  power  is  applied  at  a  point  as  far  upon 
the  root  as  the  mechanical  and  other  opportunities  of  the  case  will 
permit,  the  apparatus  becomes  a  lever  of  the  third  kind,  the  power 
being  directed  to  a  movement  of  the  entire  root  in  the  direction  of 
the  applied  force." 

This  proposition  is  made  plain  by  reference  to  the  diagrams. 
In  Fig.  258  let  A  be  a  point  upon  a  central  incisor  at  which  force 
is  applied  in  the  direction  indicated  by  the  arrow,  then  will  the 
opposing  wall,  B,  of  the  alveolar  socket  near  its  margin  receive 
nearly  all  of  the  direct  force ;  and  in  proportion  to  its  resistance 
will  there  be  a  tendency  to  move  the  root  in  the  opposite  direc- 
tion. This  proposition  will  also  hold  good  even  if  we  apply  the 
force  at  A,  Fig.  259,  or  as  far  upon  the  root  as  may  be  permitted 
"by  attaching  a  rigid  upright  bar,  C,  to  the  anterior  surface  of  the 


462 


MECHANICAL    DENTISTRY. 


crown;  the  only  difference  being  that  we  distribute  the  direct 
force  over  a  greater  area.  But  if,  as  in  Fig.  260,  we  attach  to  the 
lower  end  of  C  a  traction  wire  or  bar,  F,  and  further  enforce  the 
mechanical  principles  of  our  machine  by  uniting  its  posterior 
attachment  to  the  anchorage  of  the  power  bar,  P,  we  will  have 
neutralized  our  anchorage  force  materially  and  created  an  inde- 
pendent static   fulcrum  at  D.     Our  apparatus  now  will   distribute: 


Fig.  258. 


Fig.  259. 


its  force  over  the  entire  root,  and  give  us  complete  direction  and 
control  of  whatever  power  we  put  into  it.  The  entire  tooth  can- 
be  carried  forward  bodily,  or  either  end  can  be  made  to  move  the 
more  rapidly.  The  force  thus  directed  to  the  ends  of  the  roots 
will  have  an  increased  tendency  to  move  the  more  or  less  yielding 
and  cartilaginous  bone  in  which  they  are  imbedded. 


Fig.  260. 


An  apparatus  for  moving  the  roots  of  the  anterior  teeth  in  a 
posterior  direction,  as  in  Case  2,  is  constructed  quite  similarly,  the 
direction  of  the  two  forces  being  reversed.     See  Fig.  261. 

Protruding  Apparatus. — In  constructing  an  apparatus  for  forc- 
ing the  roots  and  adjoining  bone  of  the  anterior  teeth  forward, 
wide  German  silver  banding  material  for  the  teeth  should  be 
selected,    that    is,    T7.5f.f.   or  -  6.  --    of    an    inch    in    thickness.     This. 


CORRECTION    OF   DENTAL    IRREGULARITIES. 


463 


should  be  fitted  to  the  crowns  of  the  anterior  teeth  near  the  mar- 
gins of  the  gum,  perhaps  extending  beneath  the  margins  on  the 
proximal  sides.  Then  bars  of  No.  15  B.  and  S.  G.  wire,  slightly 
flattened,  should  be  soldered  to  each  of  the  bands  in  an  upright 
position,  and  bent  so  as  to  lie  along  the  anterior  surface  of  the 
crowns  from  the  apex  to  where  the  bars  join  the  band;  here  they 
should  take  a  direction  somewhat  parallel  to  the  gum,  but  free 
from  the  surface  to  about  y]g  of  an  inch  above  its  margin,  at  which 
point  they  should  be  flattened  or  thinned,  so  as  to  be  more  easily 

Fig.  261. 


Protruding   apparatus    in   position. 


bent  forward,  and  firmly  clasped  around  a  rigid  bar  which  is  made 
to  extend  from  anchorage  tubes  attached  to  the  posterior  teeth. 
See  Fig.  261. 

The  upright  bars  are  now  made  of  slightly  heavier  material,  and 
made  to  rest  in  front  of  the  power  bar,  and  cut  off  even  with  its  top 
edge,  when  they  are  thinned  and  rounded,  as  shown  in  the  illustration. 

This  bar,  which  should  be  very  rigid,  is  drawn  without  anneal- 
ing from  a  No.  9  extra  hard  German  silver  wire  to  No.  15  B.  and  S. 
G.  The  ends  are  threaded  in  the  No.  4  hole  of  the  Martin  screw- 
plate,   and  the  central   portion   is   slightly   flattened   in  the   rollers. 


464  MECHANICAL   DENTISTRY. 

Then  it  should  be  bent  so  as  to  rest  when  in  proper  position  in 
the  unclasped  ends  of  the  upright  bars  that  have  been  left  open 
to  receive  it.  Before  placing  it  in  position,  the  nuts  should  be 
screwed  on  to  work  at  the  anterior  ends  of  the  tubes. 

This  apparatus  can  be  made  to  exert  an  exceedingly  powerful 
force,  but  if  put  into  practical  use  as  it  now  stands,  the  ends  of  the 
roots  and  the  adjoining  bony  structure  would  not  be  forced  forward, 
notwithstanding  the  fact  that  the  power  is  applied  directly  to  the  roots 
somewhat  above  the  crevices.  The  crowns  and  the  body  of  the 
roots,  with  a  portion  of  the  alveolus  only,  would  be  moved  forward. 

To  complete  the  apparatus,  therefore,  the  fulcrum  should  be 
removed  from  the  anterior  alveolar  plate  and  placed  so  that  the 
power  can  be  applied  between  it  and  the  ends  of  the  roots  to  be 
moved.  In  other  words,  the  crowns  should  be  restricted  or  con- 
trolled in  movement  so  that  the  applied  force  may  be  directed  to 
the  roots  alone. 

This  is  accomplished  by  a  second  bar  much  smaller  and  thinner 
than  the  first,  but  proportionately  rigid,  which  rests  in  depressions 
in  the  upright  pieces  along  the  occluding  ends  of  the  teeth.  The 
ends  of  the  fulcrum  bar  are  threaded  and  passed  through  tubes  that 
are  soldered  to  the  anchorage  bands  on  each  side  below  the  power 
bar  tubes,  with  nuts  which  work  posteriorly  to  the  tubes. 

Retruding  Apparatus. — An  apparatus  for  reducing  a  promi- 
nence of  the  features  by  exerting  a  posterior  force  upon  the  roots 
and  alveolus  of  the  anterior  teeth,  is  constructed  in  a  similar  man- 
ner to  the  one  just  described,  with  the  following  exceptions: 
(1)  The  bands  should  be  fitted  to  the  crowns  of  the  incisors  near 
their  occluding  ends,  for  the  purpose  of  obtaining  a  more  rigid 
bearing  in  the  changed  application  of  force.  (2)  The  lower  ends 
also  of  the  upright  pieces  should  be  made  to  clasp  the  fulcrum  bar. 
(3)  The  nuts  should  be  reversed  in  their  relative  positions  to  the 
tubes.  (4)  The  most  difficult  and  equally  important  part  of  our 
task  will  now  consist  in  moving  the  roots  of  the  cuspids,  if  they 
are  prominent,  but  their  position  is  such  if  much  force  is  applied 
with  the  present  arrangement  of  the  apparatus,  the  bars  will  slip 
through  the  clasps  at  the  ends  of  the  upright  pieces.  Therefore 
some  provision  should  be  made  to  prevent  this,  which  may  be 
accomplished  by  short  sections  of  pipe  clasped  around  and  soft 
soldered  to  the  bars. 


CORRECTION   OF   DENTAL   IRREGULARITIES. 


46; 


The  most  modern  method  of  constructing  the  retruding  appara- 
tus is  well  shown  in  Figs.  262  and  263. 

In   considering   the   mechanical   qualities    of   the   contouring   ap- 


Fic.  262. 


paratus  outlined,  we  wish  to  direct  attention  to  the  fact  that 
the  force  expended  at  the  anchorage  attachments  is  largely  neu- 
tralized by  the  reciprocating  influence  of  the  two  forces,  and  this 

Fig.  263. 


Retruding  apparatus   in   position. 


reciprocation  is   always   equal   to  the   power   used  on  the   fulcrum 
bar    in    preventing    a    movement    of    the    occluding    ends    of    the 
crowns.     The   balance   of   the   power,   which   may   be   considerable 
30 


Fig.  264. 


November,    1892. 
Fig.  265. 


April,   1893. 
Case  i. — Half-tone  copies  of  photographs  of  plaster  casts,  made  before  and  after 
(466;  completion. 


Fig.  266. 


Fig.  267. 


November,   1892.  April,   1893. 

Model    from    occlusion    impression. 


Fig.   268. 


Fig.  269. 


After   extraction   of   inferior   bicuspids. 


Fig. 

270. 

Fig.  271. 

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Case  i. — Notice  the  upright  position  of  the  superior  teeth  in  Figs.  267  and  269, 
notwithstanding  the  expansion  and  extension  of  the  arch  as  shown  in  com- 
paring Figs.  270  and  271. 

(467) 


Fig.  272. 


November,  1892. 
Fig.  273. 


June,  1893. 
Case  2. — The  entire  operation  in  this  case  was  accomplished  with  appliances  at- 
(468) 


tached  to  the  superior  teeth  alone. 


Fig.  274. 


Fig.  275. 


November,   1892. 


June,    1893. 


Fig.   278 


Fig. 


Case  2. — Notice  the  deep  incisive  fossre  and  the  posterior  position  of  the  superior 
incisors  and  alveolus,  as  shown  in  Figs.  274,  276,  and  278,  and  compare  with 
Figs.  275,  277,  and  279 ;  the  upright  position  of  the  incisors ;  the  forward 
movement   of  adjoining  bone. 

Notice  also,  in  this  and  other  cases,  the  occlusion  of  the  posterior  teeth,  before 
and  after  treatment,  showing  that  nearly  all  change  has  been  produced  ante- 
rior to  the  bicuspids.  (469) 


Fig.  280. 


(470) 


August,  1893. 
Case  3. 


CORRECTION  OF  DENTAL  IRREGULARITIES. 


471 


in  the  general  movement  of  the  parts,  must  be   sustained  by  the 
anchorage  teeth,  if  not  further  neutralized  by  other  auxiliaries. 

When  the  central  features  of  the  face  are  depressed,  with  anterior 
superior  teeth  occluding  posteriorly  to  the  lowers,  accompanied 
with  the  usual  real  or  apparent  prognathous  lower  jaw,  great  re- 
ciprocating force  may  be  beneficially  obtained  from  the  rubber 
bands  before  mentioned.  Rubber  rings  are  cut  from  a  ^  of  an 
inch  rubber  regulating  tube  of  good  heft,  and  passed  over  the  pro- 
jecting ends  of  the  anchorage  tubes  on  the  upper  appliance  to 
buttons   on   a   lower   appliance,    opposite   the   first   bicuspids.     The 


Fig.  282. 


Fig.  283. 


April,  1893.  August,  1893. 

Case  3. — In  this  case  the  roots,  as  well  as  the  crowns,  of  the  superior  incisors 
have  been  forced  to  a  more  posterior  position,  reducing  the  prominence  of  the 
nasal  spine  of  the  superior  maxillary  and  an  exceedingly  unpleasant  fullness 
of  the  upper  lip  where  it  merges  into  the  nasal  septum.  See  Figs.  280  and 
281. 


latter  appliance  may  be  so  constructed  that  the  force  will  be  dis- 
tributed to  all  the  inferior  teeth,  and  indirectly  to  the  jaw,  forcing 
it  to  a  more  posterior  position.  Or  it  may  be  that  the  first  bicus- 
pids have  been  extracted,  as  in  Case  I,  for  the  purpose  of  forcing 
the  six  anterior  teeth  back.  In  either  case  the  elastic  force  of  the 
rubber  bands  can  be  made  to  do  effective  work  to  the  full  extent 
of  their  power  on  both  the  upper  and  lower  jaws,  neutralizing  force 
which  otherwise  would  be  expended  upon  a  static  anchorage.  In 
writing  of  this  apparatus,  Dr.  Case  says : 

"  They  are  useful  also  as  an  auxiliary  to  the  reduction  of  a  prog- 


472 


MECHANICAL   DENTISTRY. 


nathous  upper  jaw  by  reversing  their  attachments.  In  these  cases  I 
also  make  use  of  the  occipital  force,  largely  for  the  advantage  I  ob- 
tain in  forcing  the  anterior  teeth  further  into  their  sockets.  Cases 
of  prognathous  upper  jaw  with  protruding  teeth  are  rare  in  which 
there  is  not  an  abnormal  prominence  at  the  base  of  the  nose  of  the 
bones  that  sustain  the  septum  and  wings  of  the  nose.  When  force 
is  applied  to  the  crowns  alone  of  the  anterior  teeth,  this  prominence 
may  become  more  pronounced,  even  though  the  position  and  appear- 
ance of  the  teeth  and  the  face  are  improved  by  the  operation. 

"  In  these  cases,  therefore,  I  consider  it  quite  as  important  to 
move  the  roots  as  well  as  the  crowns  of  the  anterior  teeth,  when 
by  so  doing  I  find  I  am  able  to  remove  the  entire  deformity,  and 
greatly  improve  the  general  form  of  the  face,  as  seen  in  Case  3. 

"  In  giving  a  history  of  the  cases  I  shall  not  enter  into  a  specific 
description  of  the  methods  employed  in  each  particular  case,  but 
will  allow  them  '  to  speak  for  themselves.' 

"  Case  1. — Ruby  S.,  aged  fourteen,  commenced  treatment  Novem- 
ber 22,  1892.  Final  models  made  April  25,  1893.  Correction  com- 
pleted. 

"  Case  2. — Phcebe  B.,  aged  thirteen,  commenced  treatment  No- 
vember 29,  1892.  Final  models  made  June  3,  1893.  Correction 
completed. 

"  The  entire  change  in  this  case  was  accomplished  with  the  con- 
touring apparatus  on  the  upper  teeth  alone  without  auxiliaries. 

"  Case  3. — Helen  S.,  aged  thirteen,  commenced  treatment  April  5, 
1893.     Final  models  August  13,  1893.     Correction  incomplete. 

"  In  this  case  the  masticating  occlusion  of  the  teeth  permitted  the 
inferior  incisors  to  strike  the  gums  considerably  posterior  to  the 
superior  incisors,  making  it  necessary  to  lengthen  the  bite  of  the 
posterior  teeth  and  shorten  the  anterior.  This  was  accomplished 
by  a  plate  covering  the  roof  of  the  mouth,  which  received  the  bite 
of  the  anterior  inferior  teeth,  and  by  temporary  crowns  upon  the 
first  inferior  molars.  A  small  but  very  flexible  German  silver  wire, 
with  the  ends  resting  in  tubes  in  the  buccal  sides  of  the  crowns,  was 
sprung  down  under  hooks  on  the  sides  of  the  bicuspids  and  then 
up  over  similar  hooks  attached  to  the  incisors  near  their  occluding 
ends.  This  raised  the  bicuspids  and  tended  to  force  the  incisors 
further  into  their  sockets. 

"  A  simple  traction  bar  encircled  the  upper  teeth  with  anchorage 


CORRECTION  OF  DENTAL  IRREGULARITIES.  473 

tubes  and  screws  on  the  molars.  At  the  same  time  a  rubber  piece 
was  fitted  to  the  anterior  superior  teeth  with  occipital  pressure, 
which  forced  them  and.  the  alveolus  up  and  back.  I  soon  found 
that  this  apparatus  forced  the  crowns  of  the  teeth  back  only,  with 
an  apparent  tipping  of  the  roots  forward,  increasing  the  facial 
prominence  at  the  base  of  the  nose,  since  which  time  the  con- 
touring apparatus  has  been  worn,  with  all  the  force  directed  to  the 
posterior  movement  of  the  roots  alone.  The  case  now  promises  a 
perfect  result,  as  may  be  seen  by  the  models.     (Figs.  280  and  281.)" 


CHAPTER  XXX. 
ARTIFICIAL  CROWNS. 

Introductory  Remarks. — Though  the  proper  construction  of  a 
modern  collar  crown  or  bridge  denture  requires  much  scientific  in- 
formation, unusual  skill,  and  sound  judgment,  a  great  portion  of  the 
work  entailed  is  necessarily  done  in  the  laboratory.  It  should, 
therefore,  have  a  place  in  every  work  embracing  the  subject  of 
dental  prosthesis ;  it  demands,  in  fact,  a  distinctive  place,  as  it 
is  one  of  the  most  important  and  exacting  branches  of  dental 
practice. 

As  Dr.  George  Evans  has  well  said,  modern  crown-  and  bridge- 
work,  properly  understood  and  properly  performed,  takes  high 
rank  in  dental  art,  and  offers  wide  scope  for  versatility  of  talent 
and  inventive  genius.  The  varied  and  complicated  cases  presented 
for  treatment  frequently  suggest  to  the  expert  novel  contrivances 
and  methods  of  construction  and  application.  Successful  practice 
of  crown-  and  bridge-work  depends  upon  a  thorough  mastery  of 
the  underlying  principles  and  expertness  in  the  processes  involved, 
governed  by  sound  judgment  and  perfect  candor.  When  practised 
by  dentists  possessing  the  requisite  attainments  and  governed  by 
correct  ethical  principles,  it  gives  results  which  are  gradually 
establishing  its  value,  removing  erroneous  impressions,  and  insur- 
ing a  wide  professional  and  public  endorsement. 

There  are,  however,  limits  to  the  utilization  of  these  means  of 
support.  There  are  many  roots  wholly  unsuitable  for  the  purpose. 
The  operation  may  be  said  to  be  valuable  in  proportion  as  the 
artificially  crowned  root  can  be  made  comfortable,  serviceable,  and 
durable.  A  pulpless  root  that  is  extensively  disintegrated,  or  that 
is  greatly  denuded  from  excessive  absorption  of  the  surrounding 
alveolus,  or  very  loose  in  consequence  of  extended  destruction  of 
the  investing  membranes,  cannot,  in  any  sufficient  degree,  meet 
these  requirements.  Between  these  extreme  conditions  on  the  one 
hand,  and  those  associated  with  partially  crownless  roots  with  the 

474 


ARTIFICIAL    CROWNS.  475 

pulp  intact,  the  investing  membranes  free  from  disease,  the  cervical 
portions  of  the  bony  structure  unimpaired  by  decay,  and  a  firm 
attachment  to  the  socket,  conditions  representing,  on  the  other 
hand,  an  opposite  extreme,  there  are  graduations  of  normal  and 
abnormal  states,  which,  while  they  may  not  exclude  the  operation, 
must  in  some  degree  impair  its  value.  Any  estimate  of  the  ab- 
solute value  of  this  method  of  substitution  that  excludes  a  recog- 
nition of  this  fundamental  truth  is  a  false  and  unwarranted  one, 
and  there  can  be  no  rational  prognostication  in  these  cases  that 
does  not  admit  this  truth  as  an  essential  element  in  forecasting 
results. 

Not  only  will  results  be  modified  by  conditions  immediately 
associated  with  the  root  to  be  operated  on,  but  also,  to  some  extent, 
by  the  general  health  of  the  mouth.  Any  abnormal  states  of  either 
the  hard  or  soft  tissues,  or  the  presence  of  foreign  deposits,  will  act 
as  predisposing  causes  in  the  development  of  unfavorable  conditions 
whenever  the  root  operated  on  has,  previous  to  curative  treatment, 
been  morbidly  affected,  and  especially  if  such  diseased  conditions 
have  been  somewhat  virulent  and  of  long  standing.  It  is  best,  there- 
fore, in  all  cases  to  inspect  the  mouth  carefully  before  attaching  the 
crown,  and  if  any  of  the  remaining  teeth  are  found  carious  or  in- 
crusted  with  tartar,  or  the  mucous  membrane  and  gums  are  in- 
flamed or  otherwise  diseased,  appropriate  treatment  should  be 
directed  to  the  correction  of  such  abnormal  conditions  as  may  be 
present. 

In  the  less  favorable  class  of  cases,  or  where  the  root  has  been 
previously  diseased,  though  subsequently  restored  to  a  healthy  con- 
dition, any  diathesis  or  constitutional  tendency  predisposing  to  in- 
flammation or  suppuration  may  become  a  factor  in  the  develop- 
ment of  unfavorable  results.  Whenever  this  predisposition  exists 
in  any  marked  degree,  the  operation  should  be  performed  in  the 
most  careful  manner,  avoiding,  as  far  as  possible,  all  sources  of 
irritation  in  the  use  of  stones,  saws,  drills,  and  in  tapping  and 
malleting,  and  especially  in  the  use  of  excising  forceps  for  the  re- 
moval of  any  remaining  portions  of  the  crown.  Should  any  ten- 
derness or  loosening  of  the  root  supervene  after  its  necessary 
preparation,  and  before  setting  the  crown,  it  will  be  prudent  to 
defer  the  completion  of  the  operation  until  there  is  a  subsidence  of 
the  morbid  conditions,   for  if,  by  reason  of  such  irritation  or  in- 


476 


MECHANICAL   DENTISTRY. 


Fig.  284. 


flammation,  suppuration  should  be  reestablished,  it  may  be  neces- 
sary to  free  the  pulp  canal  and  renew  treatment  through  the  apical 
foramen. 

The  success  of  the  operation  may  also  be  greatly  impaired  by 
careless,  hurried,  and  injudicious  manipulation;  as  where  the  re- 
maining portions  of  the  natural  crowns  of  the  tooth  are  violently 
removed  with  excising  forceps,  by  the  unskilful  use  of  instruments 
in  dressing  the  root,  by  drills  in  enlarging  the  central  cavity,  by 
undue  or  misapplied  force  in  the  final  adjustment  of  the  artificial 
crown,  or,  finally,  by  a  faulty  position  of  the  tooth  of  replacement, 
by  which  the  root  is  subjected  to  injurious  strain,  either  by  lateral 
pressure  or  premature  closure  against  those  of  the  opposite  jaw. 
By  the  operation  of  either  or  all  of  these  causes,  disease  of  a  more 
or  less  intractable  character  may  be  induced 
which  will  impair  the  usefulness  of  the  arti- 
ficial organ  and  subject  the  patient  to  much 
annoyance. 

Preparation  of  the  Root. — In  the  process 
of  preparing  the  root  for  the  attachment  of  an 
artificial  tooth,  all  remaining  portions  of  the 
natural  crown  should  first  be  removed  with 
suitable  instruments.  If  the  cervical  portion 
of  the  tooth  is  comparatively  sound  and  un- 
broken, this  may  be  most  expeditiously  ac- 
complished, and  with  less  risk  of  injury  to 
the  root,  by  cutting  two  parallel  grooves,  opposite  each  other,  on 
the  labial  and  palatal  surfaces,  with  a  small  circular  saw,  or  a  hard 
rubber  or  rubber  and  corundum  disc.  These  grooves  should  be 
cut  through  the  enamel  deep  into  the  dentine.  Then,  with  the  excis- 
ing forceps,  the  cutting  edges  of  which  are  placed  in  the  grooves,, 
the  crown  is  readily  severed  from  the  root. 

After  the  use  of  the  disc  and  excising  forceps,  any  remaining 
portions  projecting  beyond  the  free  margins  of  the  gum  should  be 
removed,  and  proper  shape  given  to  the  end  of  the  root.  A  flat- 
edged  corundum  stone  or  what  are  known  as  the  Ottolengui  root 
facers  (Fig.  284)  are  the  best  for  the  purpose,  and  when  in  use  the 
stones  should  be  kept  constantly  wet  and  free  from  clogging  par- 
ticles of  tooth  substance.  The  end  of  the  root  should  be  dressed 
down,  anteriorly,  a  little  below  the  free  margin  of  the  gum,  care 


ARTIFICIAL    CROWNS.  477 

being  taken  not  to  cause  unnecessary  laceration ;  in  this  way 
the  artificial  crown,  when  adjusted  to  the  root,  will  unite  so 
intimately  with  the  gum  in  front,  in  ordinary  cases,  as  to  render 
exposure  unnecessary.  The  surface  of  the  root  prepared  in  this 
manner  will  present  a  concavity  corresponding  with  the  festoon  of 
the  gum. 

If  a  living  pulp  remains  in  the  root,  it  will  not  ordinarily  be 
practicable — unless  there  is  partial  obliteration  and  consequent 
recession  of  the  pulp  cavity  as  the  result  of  ossific  deposits — either 
to  cut  off  the  tooth  on  a  line  with  the  gum,  or  even  transversely,  or 
to  dress  the  root  even  with  the  gum,  without  inflicting  insufferable 
pain.  It  will  be  necessary,  therefore,  under  such  circumstances, 
either  to  devitalize  and  extirpate  the  pulp  through  the  carious 
opening  in  the  crown  before  the  latter  is  removed,  or,  if  not  ex- 
posed by  excising  the  tooth,  through  an  opening  into  the  pulp,  made 
with  a  drill  revolved  by  the  dental  engine,  after  excision. 

Devitalization  of  the  Pulp. — There  are  several  ways  of  extir- 
pating a  dental  pulp.  One  of  the  older  and  still  not  uncommon 
methods  of  operating  consists,  first,  in  devitalizing  it  with  arsenious 
acid  and  then  removing  it  with  a  broach.  Another  method  prac- 
ticed by  some  is  to  thoroughly  expose  the  pulp,  apply  cocain,  and 
then  extract  the  pulp  with  a  broach. 

Excision  of  Crown  and  Instantaneous  Extirpation  of  the  Pulp. 
— A  somewhat  heroic  method,  though  one  with  which  some  opera- 
tors have  much  satisfaction,  by  which  a  living  pulp  may  be  quickly 
and  successfully  removed,  with  comparatively  little  pain,  consists 
in  cutting  the  labial  and  palatal  grooves  as  has  been  directed,  mak- 
ing them  as  deep  as  possible,  without  inflicting  too  much  pain; 
then,  with  the  excising  forceps,  the  cutting  edges  of  which  are 
inserted  in  these  grooves,  the  crown  is  quickly  severed  from  the 
root.  This  usually  leaves  the  pulp  fully  exposed  and  paralyzed, 
when  a  piece  of  orange  wood — previously  cut  and  shaped  to  about 
the  size  of  the  canal,  not  larger,  and  the  point  saturated  with 
carbolic  acid — is  carefully  placed  against  the  exposed  point  of  the 
pulp  and  quickly  driven,  with  one  light  blow  from  the  mal- 
let, into  the  pulp  canal.  When  the  wood  is  withdrawn,  the 
pulp  often  adheres  to  it ;  if  not,  it  may  be  quickly  and  painlessly 
removed  with  a  broach.  In  this  operation  the  immediate  paralysis 
induced   renders   it   comparatively   painless.     Still   another   method, 


478 


MECHANICAL   DENTISTRY 


Fig.  285. 


and  a  very  satisfactory  one,  is  to  remove  the  pulp  while  the  patient 
is  under  the  influence  of  a  general  anesthetic. 

Preparation  of  the  Pulp  Canal. — After  the  removal  of  the  pulp 
the  apical  foramen  should  be  thoroughly  closed  by  any  method 
usually  employed  in  root  filling.  A  neglect  of  this  impor- 
tant measure  will  greatly  endanger  the  success  of  the  opera- 
tion. 

The  proper  treatment  and  preparation  of  the  root  having  been 
thus  far  accomplished,  the  canal  of  the  latter  should  next  be  en- 
larged for  the  reception  of  a  dowel-pin.  This  is  effected  with  an 
ordinary  fissure  drill  or  root  reamers  (Fig.  285). 

The  natural  opening  in  the  root  should  be  enlarged  to  the  depth 
of  two  or  more  lines,  according  to  the  length  of  the 
root;  and  the  orifice  should  be  made  large  enough 
to  admit  a  support  of  sufficient  size  to  secure  the 
crown  firmly  in  position.  The  direction  of  the  drill 
in  cutting  should  follow  closely  that  of  the  natural 
canal  in  the  root,  since  but  a  slight  deviation  in  this 
respect  may  endanger  the  integrity  of  the  latter  by 
too  great  a  thinning,  or  actual  perforation,  of  its  walls. 
The  face  of  the  root  should  then  be  given  a  suitable 
shape  for  the  reception  of  the  form  of  crown  to  be 
attached,  the  methods  of  fitting  and  inserting  which 
will  now  be  considered,  the  simple  or  all  porcelain 
system  being  first  taken  up. 

Porcelain  Crowns. — The  system  of  using  all  por- 
celain crowns  has  a  number  of  advantages,  and  at  the 
same  time  there  are  strong  reasons,  we  think,  for  using  another 
system — known   as   the   ferrule  or   collar   crown — in  all   favorable 
cases. 

The  porcelain  crown  is  especially  useful  where  an  inexpensive 
and  quickly  adjusted  crown  is  necessary;  or  where  some  patho- 
logical condition  would  seem  to  limit  the  probable  permanency  of 
an  operation,  or,  again,  where  a  temporary  crown  is  desired  to 
serve,  as  is  sometimes  necessary,  until  the  patient  or  operator  can 
make  suitable  engagements  for  more  permanent  work. 

The  objections  made  to  the  use  of  this  class  of  crowns  for  per- 
manent work  are  that  the  pin  or  post  upon  which  almost  the  entire 
support  of  the  crown  is  thrown  acts  as  a  lever  in  the  root  canal, 


ARTIFICIAL    CROWNS.  479 

and  sooner  or  later  many  of  the  weaker  roots  are  fractured,  thus 
ending  their  usefulness  as  a  support;  and  again,  the  pin  or  post, 
entering,  as  it  does,  deeply  into  the  body  of  the  porcelain,  weakens 
it  at  this  point,  and  not  infrequently  do  patients  return  with  the 
crowns  fractured  through  the  center  from  the  force  of  mastication. 
Then,  again,  when  the  crowns  are  set  with  amalgam,  which  is  the 
practice  of  many,  the  discoloration  at  the  line  of  union  with  the 
root,  if  subsequently  exposed,  is  very  objectionable. 

The  all-porcelain  crowns  may  be  divided  into  two  classes :  First, 
those  having  one  end  of  the  pin  or  post  baked  in  the  porcelain 
when  the  crown  is  made,  such  as  the  Logan,  Brown,  and  new  Rich- 
mond; second,  those  attached  to  the  root  by  a  pin,  post,  or  screw, 
one  end  of  which  is  first  cemented  in  the  root  and  the  other  after- 
ward to  the  crown.  Of  this  class  we  have  the  Bonwill,  How,  Gates, 
Foster,  and  Howland. 

After  deciding  upon  the  form  of  crown  to  be  used,  one  should 
be  selected  to  correspond  as  nearly  as  possible  in  size  and  general 
configuration  with  its  fellow  on  the  opposite  side,  and  to  harmonize 
in  color  with  those  immediately  adjoining.  The  manner  of  prepar- 
ing and  adjusting  each  of  the  crowns  named  will  be  taken  up  in 
the  order  given. 

The  Logan  Crown. — The  Logan  crown,  invented  by  Dr.  M. 
L.  Logan,  is  probably  of  all  these  the  one  most  extensively  used. 
The  method  of  adjusting  and  mounting  is  given  in  all  its  details  in 
the  following  article  by  Dr.  W.  S.  How : 

"  Fig.  290  shows  a  superior  right  central  root,  an  end  appearance 
of  the  same,  and  a  Logan  crown,  front  view.  Fig.  185  exhibits,  at 
a  right  angle  to  the  plane  of  the  first  figure,  the  same  root,  its  end, 
and  the  Logan  crown,  side  view.  In  both  figures  the  root  canal 
is  supposed  to  have  been  first  drilled  to  a  gaged  depth  with  an 
engine  twist-drill,  No.  154,  and  then  enlarged  by  means  of  a  fissure- 
bur,  No.  70,  to  the  tapering  form  shown;  the  walls  being  subse- 
quently grooved  with  an  oval  bur,  No.  90.  The  enlarged  section 
(Fig.  292)  shows  the  crown  adjusted  on  the  root  by  means  of 
cement  or  gutta-percha,  which  surrounds  the  post  and  fills  all  the 
spaces  in  the  root  and  crown.  Fig.  293  shows  the  completed 
crown.  Fig.  294  exhibits  a  bifurcated  bicuspid  root,  its  end  appear- 
ance, and  a  Logan  crown  adjusted  to  the  root.  Fig.  295  illustrates 
the  best  manner  of  bending  the  post.     Fig.  296  shows  a  split  post, 


480 


MECHANICAL   DENTISTRY. 


and  its  adaptation  to  a  bifurcated  bicuspid  root  is  seen  in  Fig.  297. 
Figs.  298  and  299  exhibit  the  mode  of  mounting  the  Logan  crown 


Fig.   286.         Fig.   287.         Fig.   288. 


Fig.   2i 


Fig.  290.      Fig.  291. 


Fig.  292. 


Fig.   293. 


Fig.  294. 


Fig.  295. 


Fig.  296.     Fig.  297. 


on  a  superior  molar  root,  and  Figs.  300  and  301  the  same  crown 
in  its  relation  to  an  inferior  molar  root. 


ARTIFICIAL    CROWNS. 


481 


"  The  preceding-  figures  clearly  present  to  the  mind's  eye  of  the 
expert  dentist  the  essential  features  of  the  Logan  crown  and  the 
method  of  mounting  it. 

"  The  details  are  as  follows :  In  every  instance  where  a  root  is 
deemed  ready  to  receive  its  filling,  it  should  first  be  measured 
through  its  canal  from  the  cervical  opening  to  the  apical  foramen, 
and  this  may  be  accurately  done  with  a  gage  adjustable  on  a  deli- 
cate canal  explorer.  The  same  device  serves  to  measure  the 
distance  from  the  apex  to  which  the  canal  should  then  be  filled 
(Fig.  286).  It  also  gages  the  depth  to  which  the  drill  may  be 
carried.  The  proper  degree  of  enlargement  from  the  bottom  of 
the  drilled  hole  will,  of  course,  depend  on  the  observed  size  and 
character  of  the  root.  Every  dentist  should  familiarize  himself 
with  generic  tooth  forms,  so  that  when  the  length  of  an  incisor, 
cuspid,  or  other  tooth  root  is  known,  he  can  so  nearly  determine. 


Fig.  298. 


Fig.  299. 


Fig.  300. 


Fig.  301. 


its  hidden  outlines  as  to  form  with  precision  a  corresponding  en- 
largement of  the  root  canal,  such  as  is  shown  by  the  several  cuts. 
For  preparing  the  roots,  the  Ottolengui  root  reamers  and  facers 
(see  pages  476  and  478)  are  very  desirable  instruments.  The 
reamers  are  made  in  three  sizes  to  correspond  with  the  Logan 
pins.  With  a  root  reamer  of  the  appropriate  size,  the  root  canal 
is  enlarged  to  fit  the  pin  along  its  whole  length,  and  so  hold 
the  crown  firmly,  independent  of  the  cement.  With  a  root  facer 
a  labial  slope  is  given  to  the  root  end,  so  that  the  crown  neck 
shall  fit  under  the  edge  of  the  gum.  Fig.  302  shows  the  method 
and  its  result,  and  the  cross-section  shows  how  the  cement  in- 
cases the  pin.  The  suitable  preparation  of  the  bifurcated  roots 
of  some  bicuspids  and  of  all  the  molars  is  a  matter  involving 
difficulties  of  an  unusual  character  and  requiring  good  judgment. 
The  feasibility  of  splitting  the  post  of  a  Logan  crown  to  adapt  it  to 
31 


482 


MECHANICAL   DENTISTRY. 


the  bifurcated  root  of  a  bicuspid  is  shown  in  Figs.  296  and  297. 
This  example  directs  attention  to  the  peculiar  shape  of  the  post,  in 
which  there  is  effected  such  a  distribution  of  the  metal  that  its 
greatest  strength  is  in  the  line  of  the  greatest  stress  that  will  in  use 
be  brought  to  bear  on  the  crown,  while  the  least  metal  is  found  at 

Fig.  302. 


the  point  of  the  least  strain;  the  applied  part  of  the  post  being  in 
outline  nearly  correspondent  to  that  of  the  root  itself.  The  root 
canal  is  likewise  conformably  enlarged  to  receive  the  largest  and 
stiffest  post  which  the  size  and  shape  of  the  root  will  permit. 

"  The  fitting  of  a  Logan  crown  to  a  root  may  be  done  with  a 


Fig.   303. 


Fig.   304. 


wet  stump  wheel  in  the  engine  hand-piece.  A  safe-side  crown 
corundum  wheel  (Fig.  303)  can  be  used  in  the  same  manner.  It 
also  affords  the  greatest  facility  for  the  slight  touches  required  to 
abrade  the  thin  cervical  borders  of  the  crown,  which  may  by  this 
means  be  done  without  encroachment  on  the  post. 


ARTIFICIAL    CROWNS.  483 

"  By  the  old  method  of  adapting  pivot  teeth  to  roots,  the  close 
fitting  of  the  crown  precluded  the  use  of  a  plastic  packing,  because 
its  thinness  over  the  surface  of  the  joint  made  the  packing  liable  to 
break  loose  under  the  shock  and  strain  of  use.  The  recess  in  the 
Logan  crown  obviates  this  defect  by  providing  a  receptacle  for  a 
considerable  interior  body  of  cement  that  will  be  deep  enough  to 
be  self-sustaining  internally,  and  yet  allow  the  peripheral  portions 
of  the  root  and  crown  to  approach  each  other  so  closely  that,  though 
only  a  film  of  packing  remain,  it  will  still  be  strong  enough  to  insure 
the  persistent  tightness  of  the  joint.  The  annular  boss,  if  formed 
of  amalgam,  also  adds  strength  in  some  cases  to  the  mount. 

"  When  enough  of  the  natural  crown  remains,  it  is  well  to  leave 
standing  some  of  the  palatal  portion,  and  cut  the  root  under  the 
gum  margin  at  only  the  labial  part,  as  shown  by  Fig.  287.  The 
safe-side  crown  wheel  is  especially  useful  in  such  cases  (Fig.  304). 
Thus  the  labial  joining  of  the  root  and  crown  will  be  concealed,  and 
the  other  parts  of  the  joint  will  be  accessible  for  finishing  and  keep- 
ing clean  (Fig.  288).  The  Logan  crown  may  be  ground  until  a 
large  part  shall  have  been  removed  for  adaptation  to  the  occluding 
tooth  or  teeth  without  seriously  impairing  its  strength  (Fig.  289). 
This  crown  also  in  such  cases  maintains  the  translucency,  which  is 
one  of  its  peculiar  excellences,  owing  to  its  solid  porcelain  body 
and  the  absence  of  a  metallic  backing  or  an  interior  largely  filled 
with  cement  or  amalgam. 

"  The  distal  buccal  root  of  the  natural  superior  molar  is  nearly 
always  too  small  to  receive  a  post  of  any  useful  diameter,  and  there- 
fore the  Logan  superior  molar  crown  has  but  two  posts,  which, 
like  those  of  the  inferior  molar  crown,  are  square,  and  thus  may  be 
easily  barbed,  as  may  also  the  ribbed  posts  of  the  crowns  from  the 
anterior  tooth  roots.  These  posts  are  large  enough  in  all  the 
Logan  crowns  to  answer  in  any  given  case,  and  can,  of  course,  be 
easily  reduced  to  suit  thin  or  short  roots. 

"  Any  of  the  cements  or  amalgams  may  be  used  in  fixing  these 
crowns,  but  good  gutta-percha,  softened  at  a  low  heat  and  quickly 
wrapped  around  the  heated  crown-post,  which  is  at  once  seated  in 
the  root,  forms  the  best  mounting  medium,  and  has  the  great 
advantage  of  permitting  a  readjustment,  or,  if  need  be,  the  ready 
removal  of  the  crown  by  grasping  it  with  a  pair  of  hot  pliers  or  for- 
ceps, and  holding  it  until  the  gutta-percha  is  sufficiently  softened." 


484 


MECHANICAL    DENTISTRY. 


The  Brown  Crown. — This  crown,  invented  by  Dr.  E.  Parmley 
Brown,  is  shown  in  Figs.  305  to  308.  Fig.  305  gives  a  lateral  view 
of  a  porcelain  crown,  with  an  iridioplatinum  pin  baked  in  position. 
The  pin  has  great  strength  at  the  neck  of  the  tooth,  where  the 
strain  is  heaviest,  and  this  strength  is  further  increased  by  extend- 
ing the  porcelain  up  on  to  it,  as  shown  in  the  accompanying  illustra- 
tions. 

A  front  view  of  the  same  crown  is  illustrated  in  Fig.  306.  The 
dotted  lines  show  the  shape  of  the  pin  and  the  position  which  it 
occupies  in  the  crown. 

The  pin  is  flattened  laterally,  affording  a  strong  hold  in  the  porce- 
lain without  bringing  it  too  near  the  surface  in  thin  teeth,  while  it 
also  permits  alteration  of  the  palatal  surface  of  the  crown  in  a  close 
bite  without  risk  of  weakening:  the  bodv. 


Fig.  305. 


Fig.  306. 


Fig.  307. 


Fig.  308. 


Fig.  307  is  a  view  of  the  bicuspid  crown,  in  which  two  pins  are 
provided,  one  for  each  root  of  two-rooted  bicuspids. 

Fig.  308  is  a  view  of  the  same  crown  with  the  two  pins  pressed 
together,  forming  a  single  pin  of  great  strength  for  a  single-rooted 
bicuspid. 

The  double  pin  in  the  bicuspids  prevents  the  gradual  loosening 
of  the  crown  by  the  rotary  movement  of  the  jaws  in  mastication, 
which,  acting  on  the  two  cusps,  exerts  such  leverage  as  to  some- 
times turn  and  break  down  ordinary  crowns  where  only  one  pin  is 
used. 

The  roots  are  ground  concave,  to  fit  the  crowns,  with  corundum 
points  or  a  Willard  countersink  bur,  and  close  joints  are  made 
well  under  the  gum,  the  pins  being  set  with  oxyphosphate  cement. 
The  canal  should  be  enlarged  just  enough  to  admit  the  pin,  which 
should  fit  snugly  throughout  its  entire  length,  the  better  to  dis- 
tribute the  leverage  exerted  by  the  crown,  and  thus  directly  to  in- 
crease the  strength  of  the  attachment. 


ARTIFICIAL    CROWNS. 


485 


The  New  Richmond  Crown. — Dr.  George  Evans,  in  his  treatise 
on  "  Crown  and  Bridge  Work,"  describes  the  new  Richmond 
crown  as  follows :  "  To  illustrate  and  describe  the  method  of 
mounting  this  crown,  a  superior  left  central  incisor  root  will  serve 
as  a  typical  case,  and  its  projecting  end  is  to  be  shaped  as  seen  in 
Figs.  309  and  310.     This  can  be  rapidly  done  with  a  narrow,  safe- 


Fig.  309. 


Fig.  310. 


Fig.   311. 


sided  flat  or  square  file,  the  angles  of  the  slopes  being  such  that 
the  gum  on  the  labial  and  palatal  aspects  will  not  interfere  with 
nor  be  disturbed  by  this  preliminary  work,  as  the  root  end  is  not, 
in  this  operation,  to  be  cut  quite  down  to  the  gum.  An  Otto- 
lengui  root  reamer  No.  2  is  then  employed  to  bore  out  the  root  to 
receive  the  crown-post,  which  is  of  the  same  size  and  shape  as  the 
Logan  crown-post  for  a  central  incisor. 


Fig.    312. 


Fig.    313. 


Fig.    315. 


"  The  sectional  view  (Fig.  311)  shows  the  relation  of  the  reamer 
to  the  root.  The  new  Richmond  crown  (Fig.  312)  is  then  tried  on 
the  root  (Fig.  313),  and  its  position  relative  to  the  adjacent  and 
occluding  teeth  noted.  If  the  cutting  edge  of  the  crown  is  to  be 
brought  out  for  alignment  with  its  neighbors,  the  root  can  be 
drilled  a  little  deeper,  and  the  reamer  pressed  outward  as  it  revolves, 


486 


MECHANICAL   DENTISTRY. 


to  cut  the  labial  wall  of  the  cavity.  The  palatal  root  slope  must 
then  be  filed  to  make  the  V  correspond  to  the  changed  inclination 
of  the  crown. 

"  Thus,  by  alternate  trial  and  reaming  and  filing,  the  crown  may 
be  fitted  to  the  root  and  adjusted  in  its  relations  until  the  post  has 
a  close,  solid  bearing  against  the  labial  and  palatal  walls  of  the 
enlarged  pulp  chamber,  and  the  crown  slopes  are  separated  from 
the  root  slopes  by  the  thickness  of  a  sheet  of  heavy  writing-paper. 
This  space  can  be  accurately  gaged,  and  the  root  slopes  con- 
formed to  the  crown  slopes  by  warming  the  crown  and  putting  on 
its  slopes  a  little  gutta-percha,  so  that  an  impression  of  the  root 
end  may  be  taken,  and  the  root  slopes  dressed  with  a  file  until 
the  film  of  gutta-percha  proves  to  be  of  equal  thinness  on  both 
slopes. 

"  To  permanently  attach  the  crown,  Dr.  Richmond  usually  takes 


Fig.  317. 


Fig.  31! 


a  thin,  perforated  disc  of  gutta-percha,  pushes  the  post  through  it, 
warms  the  crown,  presses  it  into  place,  and  when  cooled  removes 
it,  and  with  a  sharp  knife  trims  away  the  gutta-percha  close  to  the 
crown  neck.  He  then  warms  the  crown,  puts  a  very  little  oxy- 
phosphate  cement  on  the  post,  and  presses  the  crown  home.  Fig. 
314  shows  the  completed  crown." 

The  obvious  advantages  of  the  device  are  the  readiness  with 
which  the  slopes  of  the  root  end  may  be  shaped  with  a  file ;  the 
facility  with  which  these  slopes  may  be  given  any  angle  to  set  the 
crown  out  or  in  at  the  base,  or  at  the  cutting  edge,  or  to  give  it  a 
twist  on  its  axis;  the  certainty  that,  once  adjusted,  the  final  setting 
will  exactly  reproduce  the  adjustment;  the  assurance  that  in  use 
the  crown  will  not  be  turned  on  its  axis,  a  most  common  cause  of 
the  loosening  of  artificial  crowns ;  the  firmness  of  its  resistance 
to  outward  thrust  in  the  act  of  biting.     This  is  made  apparent  by 


ARTIFICIAL    CROWNS.  487 

Fig.  315,  wherein  it  will  be  seen  that  in  an  outward  movement  the 
crown  B  would  rock  upon  A  as  a  pivot.  The  dotted  line  D  shows 
how  the  crown  slope  is  resisted  by  the  root  slope,  which  extends 
so  far  toward  the  incisive  edge  that  a  much  firmer  support  is  given 
to  the  crown  than  if  the  resistance  should  be,  as  it  usually  is,  on 
the  line  of  the  gingival  margin  C. 

For  roots  that  have  become  wasted  below  the  gum  surface  it  is 
not  suitable,  except  in  such  cases  as  are  decayed  under  the  labial 
or  palatal  gum  margin  only,  but  have  yet  projecting  the  approximal 
portions  of  the  crown  (Fig.  316). 

The  sectional  view  (Fig.  317),  and  the  perspective  plan  views 
(Fig.  318)  illustrate  the  manner  of  mounting  these  crowns  on  this 
class  of  roots.     The  finished  crown  appears  as  in  Fig.  318. 

The  cases  for  which  this  crown  seems  specially  adapted  are 
such  as  have  some  considerable  portion  of  the  natural  crown  remain- 
ing. 

The  Bonwill  Crown. — This  was  one  of  the  first  crowns  intro- 
duced in  improved  porcelain  crown-work.  The  process  of  its 
adjustment  and  insertion  is  explained  in  a  lengthy  article  by  its 
inventor,  Dr.  W.  G.  A.  Bonwill,  from  which  the  following  is  pre- 
sented : 

"  These  all-porcelain  crowns  have  three  distinctive  features :  A 
concave  or  countersunk  base;  a  triangular  opening  from  the  base 
to  a  point  at  or  near  the  cutting  edge  of  the  incisors,  the  base  pre- 
senting to  the  labial  surface  (at  its  upper  portion  this  groove  is 
enlarged)  ;  a  peripheral  margin  or  border  resting  perfectly  flat  on 
the  root,  the  concavity  of  the  base  on  the  palatal  side  being  at  a 
much  more  acute  angle  than  on  the  approximal  sides.  An 
anchorage  is  made  in  the  incisors  by  a  depression  or  undercut 
between  the  labial  and  palatal  surfaces,  opening  on  the  latter.  In 
the  bicuspids  and  molars  the  retaining  pits  are  nearer  the  grinding 
surface. 

"  The  concave  base  of  the  crown  prevents  the  amalgam  from 
escaping  under  the  heavy  pressure  exerted  to  force  it  into  position, 
and  in  impacting  the  amalgam  and  expressing  the  mercury.  It 
allows  of  a  dense  body  of  material  around  the  metallic  pin,  giving 
the  equivalent  of  a  pin  the  whole  diameter  of  the  base  of  the 
crown.  It  leaves  no  joint,  the  crown  and  root  being  continuous. 
The  amalgam  is  so  thoroughly  hardened  at  once  by  impaction  in 


488 


MECHANICAL   DENTISTRY. 


the  double  concave  of  crown  and  root  as  to  make  a  very  firm 
operation.  It  prevents  any  possibility  of  the  crown's  twisting  upon 
the  pin  and  root.  In  the  event  of  fracture  of  the  crown,  the  con- 
vex surface  of  the  amalgam  on  the  root  makes  the  substitution  of 
a  new  crown  an  easy  operation.  It  enables  the  operator  to  fit  the 
crown  in  much  less  time ;  it  allows  a  proper  position  to  be  given 
to  the  pin,  with  less  danger  of  fracture  therefrom ;  it  permits  of  a 
larger  quantity  of  amalgam  in  the  crown,  and  is  capable  of  bear- 
ing greater  strain ;  it  makes  the  permanent  success  of  the  operation 


Fig.  319.  Fig.  320.       Fig.  321. 


Fig.  322.       Fig.  323.     Fig.  324.     Fig.  325. 


"  Fig.  319. — Sectional  view  of  an  incisor  crown  from  mesial  side,  showing  the 
undercut  at  the  point  opening  on  palatal  surface,  the  conical  base,  and  the  open- 
ing of  the  same  to  the  retaining  grooves,  with  the  exact  relations. 

"  Fig.  320. — Palatal  view  of  same  tooth  ;  a  is  the  external  opening  for  egress  of 
alloy  and  for  packing  around  the  pin.  The  dotted  lines  show  the  recess  or  under- 
cut on  the  mesial  and  distal  sides  and  near  the  point  for  retaining  the  crown,  and 
its  relation  with  the  conical  base. 

"  Fig.  321. — Grinding  surface  view  of  a  superior  molar  with  the  countersunk 
pin-holes  on  the  buccal  and  palatal  sides. 

"  Fig.  322. — Same  view  of  an  inferior  molar  with  the  pin-holes  on  the  mesial 
and  distal  sides. 

"  Figs.  323  and  324. — Sectional  views  of  a  molar  and  a  bicuspid  crown,  show- 
ing the  countersinks  and  their  relations  with  the  conical  base. 

"  Fig.  325. — Sectional  view  of  an  incisor  root,  showing  the  retaining  cuts  made 
by  the  wheel-bur  shown  in  Fig.  332. 


probable,  from  the  fact  that  it  is  absolutely  jointless,  and  secures 
immediate  solidity,  even  while  the  amalgam  is  semi-plastic.  These 
crowns  are  capable  of  resisting  the  force  of  biting  or  mastication, 
because  they  are  supported  nearly  to  the  cutting  edge  or  grinding 
surface,  the  triangular  opening  from  the  concave  base  nearly  to  the 
cutting  edge  allowing  the  pin  to  be  imbedded  in  the  labial  face  of 
the  crown  where  there  is  the  greatest  amount  of  porcelain. 

"  The  amalgam  to  be  used  as  the  medium  of  union  must  set 
quickly  and  be  very  hard.  Thus  far  I  have  found  nothing  better 
than  the  alloys  I  have  specially  prepared  for  this  line  of  work,  and, 


ARTIFICIAL    CROWNS. 


489 


though  they  are  costly,  the  superior  results  obtained  by  their  use 
amply  repay  the  cost.  I  use  No.  1  generally.  If  mixed  thick,  it 
will  set  so  quickly  that  the  operator  must  work  rapidly  to  prevent 
its  being  wasted.  In  incisor  cases  I  use  No.  3  at  the  gum  line  and 
make  a  close  joint. 


Fig.  326.         Fig.  328.         Fig.  329. 


© 


Fig.  327. 


Fig.  330. 


Fig.  331. 


Fig. 
332. 


"  Fig.  326. — End  view  of  a  canal  prepared  for  the  improved  combination-metal 
pin. 

"  Fig.  327. — End  view  of  same  canal  as  in  Fig.  326,  prepared  for  a  triangular 
pin,  showing  how  much  more  of  the  mesial  and  distal  surfaces  have  been  cut 
away  from  it  than  in  Fig.  326   for  the  improved  pin. 

"  Fig.  328. — Sectional  view  of  an  incisor  crown  and  root,  with  the  improved 
pin  in  its  relative  position  to  each,*  with  the  depressions  made  by  wheel-bur. 

"  Fig.  329. — Sectional  view  of  a  superior  molar,  with  the  large  angular  pin  in 
palatal  root  and  two  square  pins  in  the  buccal  roots,  one  being  shorter  and  not 
passing  through  the  crown. 

"  Fig.  330. — Block  of  a  molar  and  bicuspid,  showing  the  countersunk  holes  for 
pins  in  the  molar,  and  the  hole  in  the  mesial  side  of  the  second  bicuspid  where  a 
pin  is  alloyed  in  and  set  into  a  decayed  cavity  in  the  distal  surface  of  the  first 
bicuspid,  being  held  upon  the  molar  roots  and  attached  to  the  bicuspid  by  the 
alloy. 

"  Fig.  331. — Side  and  end  view  of  the  largest  sized  angular  combination-metal 
pin  with  the  stamped  serrations. f  The  square  pins  are  without  serrations  and 
double-pointed,  made  of  the  same  metal  and  of  equal  thickness  throughout. 

"  Fig.  332. — The  smallest  sized  wheel-bur  for  grooving  the  canal  for  anchoring 
the  pin  and  alloy. 


*  The  sectional  views  of  the  incisor  and  molar,  giving  the  relative  position  of 
the  pins  in  the  crowns  and  roots,  should  show  pins  of  larger  size.  The  pins  as 
furnished  should  be  filed  down  but  little.  It  is  not  absolutely  necessary  that  so 
many  serrations  should  be  made  in  the  canals  by  the  wheel-bur  for  retaining  the 
amalgam  and  pin  as  are  shown  in  the  sectional  view  of  the  root  of  an  incisor. 
While  no  serrations  are  shown  in  the  roots  of  the  molars,  it  is  understood  that  all 
the  canals  must  have  the  serrations.  The  square  pins  in  the  canals  need  no  ser- 
rations. At  the  point  where  they  occupy  the  countersink  in  the  crowns,  make 
two  or  three  very  slight  cuts  on  the  edges  with  a  sharp  file.  The  ends  can  be 
left  blunt. 

t  These  pins  are  now  made  without  serrations.  When  amalgam  is  used  for 
securing  them,  they  become  amalgamated  and  firmly  united. 


49Q 


MECHANICAL   DENTISTRY. 


"  In  preparing  the  canal,  use  first  a  small-sized,  spear-shaped 
drill,  carefully  following  the  natural  channel.  Then  follow  with  a 
larger  one,  taking  care  not  to  cut  through  the  root  near  the  apex. 
On  the  mesial  and  distal  sides  cut  away  but  little,  as  there  is  where 
fractures  are  most  liable  to  occur.  The  canal  can  be  very  tapering 
and  yet  hold  the  pin.  There  need  be  but  very  little  space  around 
the  pin.  By  all  means  save  all  the  walls  of  the  root  possible.  The 
smallest  sized  wheel-bur  may  be  used  to  make  a  thread  at  various 
points  along  the  canal  to  hold  the  amalgam. 

"  If  the  patient  exposes  the  gums  much  in  speaking  or  smiling, 
the  root  may  be  cut  down  with  the  bur  or  corundum  wheel  beyond 
the  free  edge,  to  conceal  the  joint.  With  bicuspids  and  molars  it 
is  not  necessary  to  go  below  the  gum;  a  joint  well  made  will  not 
be  observed,  and  the  strength  of  the  root  will  be  preserved.  If 
the  root  is  decayed  below  the  gum,  after  removing  the  softened 
parts  fill  it  with  alloy. 

"  It  is  not  necessary  that  the  face  of  the  root  should  be  flat ;  it 
may  be  either  concave  or  convex,  according  to  indications. 

"It  is  advantageous  to  take  an  impression  and  bite  of  the  root, 
and  make  a  model  and  articulation  in  plaster. 

"  The  crown  to  be  inserted  should  be  inspected  closely,  as  the 
retaining  undercut  in  the  incisors  and  the  depressions  in  the  bicus- 
pids and  molars  may  not  be  well  defined.  If  not,  the  crowns  are 
liable  to  work  loose.  If  the  base  has  been  ground  off  in  fitting,  the 
edges  should  be  beveled  again  to  a  fine  margin  with  a  corundum 
point.  The  crown  should  be  fitted  to  the  root  in  the  mouth,  not 
to  the  plaster  cast.  The  articulation  should  be  clear,  to  avoid  dis- 
placement. The  pin  should  be  as  large  as  the  previously  prepared 
canal  will  admit.  The  pin  must  in  every  case  be  fitted,  and  in  fit- 
ting it  file  only  on  the  plain  sides.  Leave  the  end  sharp,  to  offer 
the  least  resistance  in  passing  through  the  amalgam.  The  end  of 
the  pin  to  be  passed  into  the  crown  needs  very  little  alteration. 
The  crown,  being  open  on  the  palatal  surface  of  the  incisors,  per- 
mits a  blunt-pointed  pin  to  go  up  to  its  place.  The  middle  of 
the  pin  should  not  be  interfered  with  if  it  can  be  avoided.  It  is 
well  to  cut  the  pin  a  little  short  for  incisors,  as  it  may  not  get 
pushed  entirely  up  in  the  root  through  the  amalgam.  Small  square 
pins  arc  used  in  the  bifurcated  roots  of  bicuspids  and  in  the  buccal 
roots  of  molars.     They  can  be   sharpened  at  both  ends,   but  the 


ARTIFICIAL    CROWNS.  49 1 

outer  end  will  not  require  so  much  sharpening.  The  palatal  roots 
of  molars  will  generally  take  one  of  the  largest  thick  pins,  with  one 
square  pin  in  the  largest  and  most  accessible  buccal  root.  Each 
canal  should  have  a  pin,  if  the  canal  can  be  reached  and  properly 
prepared  to  receive  it,  even  though  the  pin  has  to  be  so  short  as 
not  to  pass  through  the  hole  in  the  crown.  If  it  enters  the  counter- 
sunk base  it  will  support  the  root.  The  lower  molars  will  require 
two  of  the  largest  sized  pins.  As  the  support  of  the  root  is  depend- 
ent upon  the  size  of  the  pin  and  the  depth  to  which  it  is  inserted, 
single-rooted  teeth  should  have  the  very  largest  thick  pin.  If  the 
root  is  thin  on  the  mesial  and  distal  sides,  the  thin,  angular  pin  is 
to  be  preferred.  Ordinarily,  these  large  pins  do  not  have  to  be  bent. 
If  necessary,  it  had  better  be  done  with  a  hammer  and  before  the 
mercury  touches  them.  The  pin  should  have  free  movement  in 
both  root  and  crown.  Should  it  be  discovered  that  the  pin  is  too 
long  after  it  has  been  packed  in  the  root,  it  can  be  cut  off  with 
sharp  forceps,  pressing  them  up  against  the  pin  to  prevent  displace- 
ment. The  pin  can  be  sharpened  subsequently  with  the  corundum 
wheel. 

"  To  insure  an  amalgamation  of  the  pin  with  the  filling,  brighten 
the  surface  of  the  former  before  inserting. 

"  The  roots,  crown,  and  pins  being  in  readiness  and  arranged  on 
the  table,  so  that  no  mistake  may  occur  from  getting  the  pin  in  the 
wrong  position,  and  the  appliances  necessary  for  the  operation 
being  at  hand,  the  alloy  preferred  should  be  mixed  a  little  thinner 
than  if  intended  for  a  filling,  especially  where  the  root  has  a  long 
canal.  The  shorter  the  canal,  the  thicker  the  amalgam  may  be 
mixed.  Mix  only  enough  at  one  time  for  one  root.  Put  enough 
amalgam  in  the  canal  to  nearly  fill  it,  but  do  not  pack  it ;  force  into 
it  a  steel  pin  made  for  the  purpose,  of  about  the  same  size  as  the 
pin,  to  make  way  for  the  easier  insertion  of  the  latter.  Then  grasp 
the  pin  with  suitable  forceps,  and  carefully  but  steadily  press  it  up 
to  its  destination.  If  you  cannot  succeed  in  doing  so,  remove  it, 
and  again  use  the  steel  pin.  When  in  place,  use  an  instrument  with 
a  point  small  enough  to  pass  between  the  pin  and  the  root,  and 
pack  by  tamping  the  amalgam  around  it.  A  piece  of  bibulous 
paper  placed  over  the  point  of  the  instrument  will  assist  materially 
in  carrying  the  amalgam  before  it.  Before  the  amalgam  has  be- 
come too  hard,  replace  the  crown  to  determine  that  the  pin  is  in 


492 


MECHANICAL   DENTISTRY. 


proper  position ;  if  not,  it  can  be  crowded  to  one  side  or  the  other 
with  the  tamping  tool.  Should  the  pin  be  found  to  be  rather  long, 
it  can  be  ground  off  with  the  corundum  wheel,  holding  it  meanwhile 
with  the  forceps.  No  attempt  should  be  made  to  bend  the  pin 
after  it  has  been  amalgamated,  for  fear  of  breaking  it.  If  any 
amalgam  has  been  left,  and  it  is  still  plastic,  it  may  be  packed 
around  the  pin  at  the  base  of  the  root,  using  the  bibulous  paper 
as  before  directed.  If  not,  mix  again  to  complete  the  operation. 
Bank  up  the  amalgam  on  the  root  high  enough  to  fill  the  base  of 
the  crown.  The  crown  should  now  be  tried  on,  and  forced  home 
with  an  adjuster  adapted  to  the  case,  removing  the  surplus  amalgam 
if  too  much,  or  adding  if  not  enough.  Remove  and  dry  the  crownj 
and  fill  up  simply  the  undercut  cavity  near  the  cutting  edge  if  an 
incisor,  or  the  depressions  in  the  crowns  of  bicuspids  or  molars, 
allowing  a  very  little  to  extend  into  the  cervical  base.  Now  force 
it  home  with  the  adjuster.  It  requires  considerable  force  to  set  one 
of  these  crowns  according  to  directions — a  force  which  cannot  be 
applied  with  a  mallet  without  danger  of  loosening  or  displacing  the 
crown.  Steady  pressure  with  slight  rotation  will  carry  the  crown 
into  place,  if  the  amalgam  is  not  too  hard  or  there  is  not  too  much 
of  it.  I  would  advise  you  not  to  attempt  to  set  a  crown  without 
an  adjuster  or  its  equivalent.  Free  mercury  will  be  squeezed  out 
on  the  palatal  surface,  which  should  be  wiped  off.  Now  hold  the 
crown  in  place  with  the  fingers,  with  the  bibulous  paper  under  the 
tamping  instrument,  and  consolidate  the  amalgam  around  the  point 
of  the  pin  in  the  crown,  absorbing  any  free  mercury  which  appears 
there.  The  excess  of  alloy  at  the  joint  must  now  be  removed, 
care  being  taken  to  press  the  crown  up  while  this  is  being  done. 
The  amalgam  packed  around  the  pin  in  the  crown  on  the  palatal 
side  should  be  as  stiff  as  may  be  to  work  readily.  It  is  well  to 
leave  over  some  of  the  first  mixing  for  holding  the  pin,  and  this 
will  be  about  right  for  consolidating  about  this  point. 

"  If,  in  a  bicuspid  or  molar  crown,  the  pin  should  come  so  far 
through  as  to  interfere  with  articulation,  it  may  be  ground  off  with 
the  corundum  wheel  while  the  crown  is  firmly  held. 

'  The  case  can  now  be  dismissed,  with  directions  for  the  patient 
to  return  the  next  day,  in  order  to  make  sure  that  the  articulation 
is  correct  and  to  dress  off  the  joint  between  the  crown  and  root, 
which  may  be  done  with  a  small,  round-headed  bur. 


ARTIFICIAL    CROWNS. 


493 


"  There  are  some  cases  in  which  the  root  cannot  be  filled  with 
anything;  if  in  a  molar,  the  pulp-chamber  can  be  relied  upon  to 
hold  a  headed  pin  or  pins.  When  a  tap-hole  is  required  in  the 
root  it  can  be  made  low  down  and  at  an  acute  angle,  and  the  amal- 
gam packed  around  the  root  canal  above  the  tap. 

"  Should  an  artificial  crown  be  broken,  another  can  easily  be 
substituted  by  burring  off  any  excess  of  amalgam,  and  using  fresh 
amalgam,  mixed  thin,  to  allow  of  ready  adjustment. 

"  Two  crowns  can  be  inserted  on  the  root  of  one  large  molar  with 
the  assistance  of  the  decayed  approximal  surface  of  an  adjacent 
tooth  (see  Fig.  330)." 

The  Porcelain  Dovetail  Tooth  Crown. — These  crowns  are 
designed  for  the  roots  of  bicuspids  and  molars  only,  and  the  process 
of  mounting  them  may  be  very  briefly  described : 

"  Fig.  333  shows  the  roots  of  an  inferior  molar  after  the  apical 


Fig.  333.       Fig.  334.         Fig.  335. 


Fig.   336.       Fig.   337. 


Fig.   338. 


portions  have  been  filled,  the  neck  recessed,  the  canals  drilled  and 
tapped,  and  two  How  screw-posts  firmly  fixed  therein,  the  ends  of 
the  posts  having  been  pinched  toward  each  other  by  means  of  a 
pair  of  pliers,  so  that  they  will  go  through  the  central  opening  in 
the  crown  (Fig.  334).  This  opening  is  of  a  dovetail  form,  as 
shown  in  cross-section  by  Fig.  335,  where  the  crown  is  seen  in 
place  over  the  posts  on  the  root.  It  is  thus  made  obvious  that  the 
crown  may  be  easily  put  on  and  off  the  root  in  the  process  of 
fitting  the  crown-neck  to  the  root-^ieck,  and  also  that,  for  occlusion, 
the  crown  may  be  ground  low  on  any  or  all  sides  without  destroy- 
ing the  dovetail  function  of  the  central  cavity.  When  the  fitting 
is  completed,  and  the  crown  cut  so  short  as  to  be  J~  of  an  inch 
distant  from  the  occluding  tooth,  amalgam  is  packed  into  the 
neck  recess,  around  the  posts,  and  thinly  over  the  cervical  margin 
of  the  root,  the  crown  put  in  place,  and,  with  thumb  pressure, 
firmly   seated.     Then  test   the   occlusion,   and   complete   the   opera- 


494 


MECHANICAL   DENTISTRY. 


tion  by  packing  amalgam  into  the  crown  opening,  which  will 
permit  the  forcing  of  the  amalgam  in  all  directions,  to  insure  a  firm 
base  for  the  crown  and  its  secure  dovetail  attachment  to  the  posts, 
as  shown  by  Fig.  335. 

"  The  bicuspid  crown  (Figs.  336  and  337)  is  similarly  mounted, 
as  may  be  seen  in  Fig.  338,  cross-section ;  the  same  crown  and 
root  being  shown  in  contour  by  Fig.  339.  In  some  instances  this 
bicuspid  crown  may,  like  the  Foster  crown,  be  secured  by  a  headed 
screw,  as  shown  in  Fig.  340.  The  root  having  been  drilled  and 
tapped  and  recessed,  and  the  crown  properly  fitted  and  articulated, 
the  screw  is  put  through  the  crown,  amalgam  packed  in  the  crown 
groove  and  around  the  screw,  which  is  then  inserted  in  the  root, 
and  the  crown  pressed  hard  into  its  place.  The  screw  is  then 
turned  into  the  position  shown  in  Fig.  340,  thus  compressing  the 
amalgam   or  cement   in  both   recess   and   groove,   after  which   the 


Fig.  339. 


Fig.  340. 


Fig.  341. 


Fig.  342. 


screw-head  may  be  covered  with  amalgam,  cement,  or  gold,  as 
desired. 

"  As  a  preferable  mode,  however,  the  screw-post  may  first  be 
fixed  in  the  root,  the  crown  adjusted  over  the  post,  amalgam 
packed  on  the  root  and  around  the  post,  the  crown  seated  firmly, 
more  amalgam  packed  in  the  crown  cavity  around  the  post,  and 
then  a  nut  screwed  on  the  post,  as  shown  in  Fig.  341.  In  all  the 
sectional  cuts  cement,  amalgam,  or  gutta-percha  is  to  be  understood 
as  filling  the  cavities  in  the  conjoined  roots  and  crowns. 

"  Fig.  342  shows  in  contour  a  dovetailed  crown  mounted  on  a 
superior  molar  root  in  the  manner  shown  by  Fig.  335.  It  is 
obvious  that  the  crown  of  Fig.  335  might  be  ground  quite  down 
to  the  post  ends,  and  yet  be  firmly  held  by  the  dovetail  sides  of 
the  central  cavity." 

The  Gates  Crown. — The  Gates  crown  is  quite  similar  to  the 


ARTIFICIAL    CROWNS. 


495 


Bonwill  crown.     It  is  usually  attached  to  the  root,  however,  by  a 
metallic  screw  manufactured  for  the  purpose,  such  as  is  illustrated 

Fig.  343. 


Fig.  344. 


in  Fig.  344,  instead  of  the  Bonwill  pin.     The  screw  is  first  inserted 
in  the  root  and  the  amalgam  packed  around  it.     In  nearly  all  roots, 
at  a  reasonable  distance  up  the  canal,  a  suitable  place  for  fastening 
the  end  of  the  screw  can  be  found.     Too  much  force 
must  not  be  applied  in  its  insertion,  as  a  root  is  easily 
split.     In  bicuspid  and  molar  crowns  nuts  are  used  on 
the  screws,  which  fit  slots  in  the  grinding  surface  of 
the  porcelain.     They  are  screwed  into  the  amalgam  or 
cement,  and  covered  with  it  in  the  process  of  cementa- 
tion of  the  crown. 

The  Foster  Crown. — The  Foster  crown  also  resem- 
bles the  Bonwill,  but  has  less  concavity  at  the  base.     The  crown  is 
attached  to  the  root  by  a  headed  screw  (Fig.  346)  or  a  screw  with 
a  nut,  instead  of  the  Bonwill  pin. 


Fig.  345. 


Fig.  346. 


The  How  screws  and  instruments  (Fig.  347)  are  best  adapted  for 
use  with  these  crowns. 


496 


MECHANICAL   DENTISTRY. 


Fig.  348.       Fig.  349.       Fig.  350. 


The  Howland  Crown. — This  crown  is  attached  like  the  How 
dovetail  crown,  with  screws  that  are  first  inserted  in  the  root. 
It  is  used  mostly  on  bicuspid  and  molar  roots,  and  consists  of  a 
hollow  porcelain  crown,  with  a  cavity  in  the  crown  sufficiently 
large  to  admit  the  screws  or  pins  (Fig.  348)  and,  when  necessary, 
a  small  portion  of  the  root. 

The  method  of  setting  this  crown,  as  described  by  Dr.  S.  E. 
Howland,  the  inventor,  is  to  trim  the  root  even  with  the  gum,  with 

a  stump  file  (a  corundum  stone  or  the  Ottolengui  root- 
Fig.  347.    facer  on  the  dental  engine,  however,  is  more  suitable)  ; 

fit  the  crown  to  the  root;  enlarge  the  root  canal  so  that 

a  threaded  pin  of  proper  size  will  pass  in  easily,  partially 

fill    the    canal    with    zinc 

phosphate,  and  press  the 

pin  to  its  place  with  pliers. 

The    crown    should    then 

be  filled  with  zinc  phos- 
phate and  pressed  to  its 

place,  care  being  taken  to 

hold   it   in    position    until 

the  cement  sets  (Fig.  349). 

If  any  operator  distrust  the  ability  of  zinc  phosphate  to 

make  a  perfect  joint,  a  small  quantity  of  silver  amalgam 

or  gutta-percha  can  be  used  to  advantage. 

The   mode   of    fastening   is    strong   and    simple,    and 

when  set,  if  a  good  joint  has  been  made,  none  of  the 
phosphate  or  other  setting  material  is  visible.  It  is  a  perfect  imi- 
tation of  the  natural  tooth  (Fig.  350). 


PORCELAIN  CROWNS  WITH  GOLD  COLLAR  ATTACHMENT. 

A  very  good  combination  for  some  cases  is  to  use  a  gold  collar, 
either  seamless  or  soldered,  in  combination  with  any  of  the  porce- 
lain crowns. 

The  root  having  been  properly  prepared  to  receive  a  collar,  it  is 
adjusted  and  adapted  the  same  as  for  the  Richmond  crown  (see 
p.  503).  The  porcelain  crown,  the  base  of  which  should  be  fully 
as  large  as  the  end  of  the  root,  is  then  ground  even  with  the  cer- 
vical walls,  and  fitted  into  the  collar,  which  should  be  trimmed 
and  burnished  to  the  form  of  the  crown.     Dr.  Townsend's  fusible 


ARTIFICIAL    CROWNS. 


497 


Fig.  351. 


metal  die,  used  in  the  following  manner,  facilitates  the  application 
of  a  collar  to  a  Logan  crown  (Fig.  351).  Prepare  the  root  canal 
to  receive  the  pin.  Grind  a  suitable  Logan  crown  to  fit,  and 
articulate  it.  Construct  a  band  of  No.  30  gold  (for  instructions 
see  p.  505),  which  should  be  wide  enough  to  project  beyond 
the  end  of  the  root  %%  of  an  inch.  Cut  a  wooden  peg  about  an 
inch  long  and  taper  one  end  of  it  to  the  general  size  and  shape  of 
the  pin  in  the  Logan  crown.  Place  the  band 
on  the  root,  insert  the  peg  in  the  canal,  and  fill 
up  the  band  with  Melotte's  moldine,  pressing  it 
closely  about  the  peg.  Remove  all  together, 
and,  holding  the  die  over  the  flame  of  an  alcohol 
lamp  to  melt  the  fusible  metal,  place  them  alto- 
gether on  the  die,  with  the  pin  in  the  socket, 
and  press  down  until  the  moldine  rests  on  the 
surface  of  the  molten  metal.  Then  carefully 
chill  the  tooth;  in  cooling,  the  fusible  metal  take's  a  firm  hold  on 
the  lower  edge  of  the  gold  band,  holding  it  securely  in  place  during 
the  remainder  of  the  operation.  Now  remove  the  peg  and  the 
moldine,  and  with  a  wooden  mallet  drive  the  Logan  crown  into 
the  band  until  the  porcelain  rests  upon  the  fusible  metal.  Burnish  the 
band  smoothly  about  the  crown.  When  it  is  perfectly  adjusted  to 
the  porcelain,  melt  the  fusible  metal  to  release  the  band  and  crown. 


Socket.     2.  Fusible 
Metal. 


Fig.  352. 


Fig.  353. 


Fig.  354. 


Fig.  355. 


If  the  work  has  been  carefully  done,  the  crown  will  then  be  ready 
to  be  adjusted  in  the  mouth. 

Enough  of  the  labial  portion  of  the  band  should  be  trimmed 
away  to  prevent  too  conspicuous  exposure  of  the  gold  (Fig. 
352). 

This  collar  combination  is  available  in  very  difficult  cases,  as,  for 
32 


498  MECHANICAL   DENTISTRY. 

instance,  when  a  root  is  decayed  upon  one  side  beneath  the  gum 
margin,  as  seen  in  Fig.  353. 

This  operation,  when  completed,  would  appear  in  vertical  sec- 
tion like  Fig.  354,  and  a  view  in  perspective  would  resemble  Fig. 

355- 

Dr.  E.  C.  Kirk's  method  of  combining  the  porcelain  crowns 
with  a  band  or  collar,  is  shown  in  Figs.  356  and  357.  Here  the 
Foster  crown  is  employed.  First  a  collar  is  made  and  fitted  to 
the  root;  it  is  cut  narrow  on  the  labial  side,  and  left  wide  on  the 
lingual,  so  that  it  shall  extend  nearly  to  the  cusp  of  the  crown  when 
finished  (Fig.  357).  The  seamless  gold  collars  are  well  suited  for 
application  to  this  style  of  crown. 

The  crown  selected  should  have  a  somewhat  greater  circumfer- 
ence at  the  base  than  the  collar,  so  that  when  ground  down  some- 

Fig.   356.  Fig.   357. 


what  conically  on  its  lingual  and  approximal  surfaces  it  can  be 
tightly  adjusted  to  the  collar,  which  would  be  impossible  if  a 
crown  smaller  than  the  collar  is  used.  The  screw  is  fitted  so  that 
it  will  hold  the  crown  in  proper  relations  with  the  root.  It  is  then 
removed  with  the  crown,  the  parts  dried,  and  the  root  canal  filled 
with  a  slow-setting  oxyphosphate  cement.  The  crown  is  then 
pressed  home,  the  surplus  cement  flowing  through  the  opening  in 
the  porcelain  and  filling  up  any  interstices  around  or  between  the 
band,  the  root,  and  the  crown.  The  screw  is  then  forced  to  posi- 
tion, and,  when  the  cement  is  set  perfectly  hard,  the  head  of  the 
screw  or  the  nut  on  it  is  notched  to  form  a  retaining  pit,  and  the 
countersink  of  the  crown  filled  with  gold. 

Dr.  C.  S.  W.  Baldwin's  method  is  to  cap  the  root  and  attach  a 
Logan  crown  in  the  following  manner : 

First,  the  root  is  shaped  for  the  proper  adaptation  of  the  band. 


ARTIFICIAL    CROWNS. 


499 


The  band  and  cap  are  then  made  as  directed  for  the  Richmond 
crown  on  page  503.  The  edges  are  then  trimmed  to  fit  the  fes- 
toon of  the  gum ;  a  hole  drilled  from  the  inner  side  for  the  pin, 
leaving  the  raggedness  made  by  drilling  to  catch  in  the  cement. 
Place  the  cap  on  the  root  and  fit  the  porcelain  crown  accurately  to 
it  in  the  desired  occlusion  and  position.  Fig.  358  shows  a  root, 
cap,  and  a  Logan  crown.  A  crown  having  the  H-shaped  pin,  but 
square  on  the  edge,  like  some  of  the  early  patterns  of  Logan  or 
Bonwill  crowns,  would  reduce  the  time  of  setting  and  give  best 
results.  Having  polished  the  edges  of  the  cap,  the  crown  may  be 
conveniently  adjusted  as  follows :  Place  oxyphosphate  cement  in 
the   countersunk   portion  of   the   porcelain,   and   in   the   canal   only 


Fig.  358. 


Fig-  359- 


Fig.  360. 


Fig.  361. 


enough  cement,  of  creamy  consistency,  to  fill  it,  as  the  pressure 
required  to  force  out  the  surplus  under  the  edges  of  the  cap  destroys 
many  nicely  adjusted  crowns,  leaving  bulging  irritants  instead  of 
smooth  supports.  If  proper  attention  has  been  given  to  fitting  the 
crown  and  root,  all  will  come  nicely  to  place;  but  in  some  cases  of 
difficult  adjustment  it  may  be  necessary  to  cement  the  crown  to  the 
cap  before  fastening  the  pin  in  the  root  (Fig.  359). 

In  most  cases  the  gold  band  will  be  invisible  and  below  the  free 
margin  of  the  gum.  There  are  instances,  where  the  anterior  teeth 
are  prominent,  in  which  it  will  be  necessary  to  cut  away  the  top  of 
the  cap  in  front,  allowing  the  porcelain  to  come  directly  in  contact 
with  the  root,  the  band  going  deeper  than  in  ordinary  cases,  which 
prevents  the  appearance  of  gold  (Fig.  360). 


500 


MECHANICAL    DENTISTRY. 


Dr.  Bomvill's  plan  is  to  cap  the  tooth  with  a  platinum  or  gold 
cap  having  a  slot,  into  which  the  pin  passes  as  it  is  slipped  on  the 
root  (Fig.  361).  The  crown  is  then  secured  with  amalgam  in  the 
usual  way. 

Dr.  Sidney  S.  Stowell's  method  is  as  follows :  Make  a  closed 
cap,  using  the  combination  crown  metal,  and  place  it  upon  the  root. 
The  cap  is  then  perforated  and  the  root  reamed  for  the  dowels. 
The  bite  in  wax  is  now  taken,  after  which  the  cap  is  burnished  into 
the  countersunk  end  of  the  root  (Fig.  363).  The  dowels  of  plati- 
num and  iridium  wire  are  now  set  in  their  places,  being  allowed  to 
project  ]/\  of  an  inch  so  that  they  may  adhere  to  the  impression 
of  plaster  which  is  then  taken.  From  this  a  cast  is  made  of  invest- 
ing material ;  calcined  marble-dust  and  plaster  is  preferable,  though 
fine  molding  sand  will  do.  The  dowels  are  now  cut  off  even  with 
the  top  of  the  cap  (Fig.  364). 

Fig.  362.    Fig.  363.    Fig.  364.    Fig.  365.     Fig.  366.     Fig.  367.     Fig.  368.  Fig.  369. 


The  tooth  to  be  used  may  be  a  Logan  or  Brown  crown,  or  a 
common  countersunk  tooth.  As  the  case  in  question  is  a  bicuspid, 
we  have  selected  for  it  a  Logan  crown.  First,  cut  off  the  pin,  and 
then  the  tooth  is  ground  into  position  on  the  cap ;  grinding  the 
stump  of  the  pin  and  porcelain  alike  evenly  and  smoothly.  The 
stump  of  the  pin  is  now  ground  with  a  small  wheel  below  the  sur- 
face of  the  porcelain  (Fig.  365).  The  tooth  is  invested  (Fig.  366), 
and  pure  gold  fused  on  to  the  platinum  pin,  and  while  in  a  fluid  state 
it  is,  with  a  wax  spatula,  spatted  down  flat  (Fig.  367).  The  gold  is 
filed  or  ground  down  even  with  the  porcelain,  and  at  the  palatal  bor- 
der the  tooth  is  ground  to  bevel  back  until  the  gold  is  reached  (Fig. 
368.  The  tooth  is  now  fastened  in  place  on  the  cap  with  wax 
cement  (Fig.  369),  the  cast  cut  away,  and  the  case  invested  in 
asbestos  and  plaster  (Fig.  370).  This  is  used  because  of  the  fiber 
of  the  asbestos,  which  prevents  the  separation  of  the  crown  and 
cap.     The  wax  is  removed  with  boiling  water,  or  is  burned  out,  the 


ARTIFICIAL   CROWNS. 


50I 


case  thoroughly  heated  up,  then  a  small  clipping  of  thin  platinum: 
plate  is  crowded  into  the  opening  (see  Fig.  370)  caused  by  the 
grinding  of  the  bevel  on  the  crown.  The  clipping  of  platinum 
serves  as  a  lead  for  the  solder,  which  follows  it  down  into  the 
countersunk  cap,  around  the  ends  of  the  dowels,  and  finally 
attaches  itself  to  the  pure  gold  already  firmly  attached  to  the  stump 
of  the  platinum  pin.  When  cool  the  case  is  removed  from  the  in- 
vestment, dressed  and  polished  (Fig.  371).  A  sectional  view  of  a 
like  tooth  (Fig.  372)  shows  the  organization  in  detail. 

Fig.  373  shows  a  central  incisor  root  on  which  a  Logan  crown  is 
used  after  this  method.  Fig.  374  shows  how  delicately  an  operation 
of  this  kind  may  be  performed  upon  an  inferior  central  incisor,  by 
the  use  of  the  countersunk  tooth  crown,  which  is  shown  as  it 
appears  before  gold  has  been  melted  in  its  cup  around  the  pin; 
when  the  cup  has  been  filled  with  gold,  and  after  the  crown  has 


Fig.   370. 


Fig.   371.         Fig.   37; 


Fig.   373. 


Fig.   374- 


Fig.   375. 


been  ground  and  beveled.  A  countersunk  molar. crown  is  shown 
as  likewise  mounted  on  the  roots  of  a  superior  left  second  molar 

(Fig-  375)- 
The  cuts  are  made  from  photographs  of  prepared  specimens,  the 

natural  roots  of  which  vary  in  the  several  figures;  and  in  the  sec- 
tion (Fig.  371)  the  continuation  of  the  pulp  canal  does  not  appear, 
because  obliterated  in  preparing  the  section. 

The  claims  for  this  method  of  crown-work  are  as  follows :  The 
combination  of  an  all-porcelain  crown  with  a  closed  cap  and  dowels; 
the  adaptation  of  which  crown  and  its  final  attachment  to  the  root 
can  be  made  perfect. 

The  dowels  may  be  set  at  any  angle  that  the  direction  of  the  root 
canal  may  indicate,  using  one  or  more  dowels  as  the  case  may  re- 
quire, and  when  the  root  has  to  be  cut  off  much  below  the  gum, 
and  a  collar  cannot  be  placed,  a  platinum   disc  floor  on  the   root 


502 


MECHANICAL    DENTISTRY. 


end  is  the  preferable  plan.  The  well  known  and  easily  detected 
plate  tooth  having  a  gold  backing  which  renders  the  tooth  dull  in 
appearance  is  thus  made  obsolete,  for  this  crown  possesses  the  trans- 
lucent appearance  of  the  natural  organ.  Best  of  all,  the  glaring 
gold  of  which  some  so-called  beautiful  crowns  are  almost  entirely 
composed  is  by  this  means  superseded.  We  here  refer  to  gold 
bicuspids  and  molars,  more  especially  to  the  former;  it  was  the 
unsightly  appearance  of  these  which  first  led  us  to  try  and  improve 
on  them. 

While  recognizing  the  unquestioned  value  of  the  closed  cap  and 
dowel,  we  respectfully  present  a  supplemental  method  which  results 
in  a  crown  possessing  all  the  merits  of  the  former  with  additional 
embodiment  of  strength,  beauty,  and  practicability. 

Dr.  Shulze's  Method. — Another  method  of  crowning,  by  using 
a  plain  rubber  porcelain  tooth  in  combination  with  a  gold  collar  is 
that   described   by   Dr.    Wm.    H.    Shulze,   Atchison,    Kansas.     The 

Fig.   376.  Fig.   377.  Fig.   378.  Fig.   379.     Fig.   380.     Fig.   381.  Fig.   382.  Fig.   383. 


doctor  says :  "  My  mode  of  utilizing  the  plain  rubber  porcelain  tooth 
for  a  bicuspid  crown  will  be  found  to  be  both  simple  and  practical. 
After  preparing  a  tooth  root  as  for  an  all-gold  crown  by  fitting 
over  the  root  neck  a  gold  collar  of  the  proper  width,  as  in  Fig. 
376,  remove  and  cut  away  the  front  of  the  collar  (Fig.  377).  Bevel 
the  labial  edge  of  the  root  so  that  the  tooth  can  set  well  into  the 
collar  (Fig.  378).  Replace  the  collar  on  the  root,  dry  out,  and 
place  a  little  softened  wax  on  the  end  of  the  root.  Select  a  suitable 
plain  rubber  tooth,  nip  off  the  heads  of  the  pins,  grind  so  that  it 
will  enter  the  collar,  adjust,  and  articulate,  pressing  the  tooth 
against  the  wax.  Carefully  remove  the  collar  and  tooth  (Fig.  379). 
Invest  in  plaster  and  asbestos  fiber  (Fig.  380).  Fit  a  thin  piece  of 
platinum  into  the  collar,  burnishing  it  down  on  the  tooth,  and 
bending  it  down  to  the  pins.  If  it  is  desired  to  use  a  post,  remove 
and  punch  the  platinum  plate  at  the  proper  place,  and  solder  in  a 
post ;  replace  within  the  collar,  and  secure  with  a  piece  of  binding 


ARTIFICIAL    CROWNS.  5O3 

wire  imbedded  in  the  investment  (Fig.  380).  A  little  18-carat  solder 
will  join  together  the  collar,  platinum  plate,  and  tooth  pins  (Fig. 
381).  If  there  are  any  places  where  the  collar  does  not  fit  the  tooth 
closely,  pack  in  gold-foil  before  soldering.  If  the  inner  cusp  does 
not  fill  the  collar,  or  it  needs  lengthening  for  occluding  purposes, 
get  the  desired  shape  with  wax  when  fitting  the  tooth.  Remove 
the  wax  after  investment,  pack  in  gold-foil  pellets,  and  add  enough 
20-carat  solder  to  flow  through  it,  and  the  desired  addition  will  ap- 
pear as  in  Fig.  382.  The  completed  crown,  mounted  as  usual  with 
cement,  is  shown  in  Fig.  383. 

The  advantages  of  this  method  are  its  simplicity,  ease  of  adapta- 
tion and  articulation,  the  short  time  required  to  fit  and  make  the 
crown,  its  strength,  security,  and  natural  appearance,  and  the  con- 
venience of  using  a  plain  rubber  or  saddle-back  tooth. 

FERRULE   OR    COLLAR    CROWNS. 

The  Richmond   Crown. — This   crown   was  originally  brought 
to  the  notice  of  the  profession  by  Dr.   C.  M.  Richmond,  of  New 
York.     Numerous  modifications  have  been  made,  however,   which 
enhance  its  value.     The  process   of   constructing  the 
improved  crown  is  as  follows :  FlG-  384- 

1.  The  root  must  be  trimmed  down  to  about  the     Stj   f=^\ 
gum  line,  except  the  labial  portion,  which  should  be     ,  j  ' 
cut  nearly  ^  of  an  inch  below  the  gum  margin.     For     I     |    I     / 
this  purpose,  corundum  stones  or  the  Ottolengui  root      \  I      |  / 
facers  are  employed,  as  shown  in  the  preparation  of      ^        W 
roots  for  the  Logan  crown.      (See  pp.  476  and  478.) 

2.  The  ring  of  enamel  remaining  upon  the  root  should  be  care- 
fully and  thoroughly  removed  (see  Fig.  384),  making  the  sides  of  the 
root  parallel,  so  that  the  band,  when  applied,  may  fit  closely  its  entire 
width.  If  this  is  not  done,  the  band,  even  if  a  narrow  one,  instead  of 
fitting  closely  will  form  a  pocket  beneath  the  gum  margin,  and  will, 
in  consequence  of  its  irritating  effect  upon  the  surrounding  tissues, 
cause  more  or  less  inflammation  and  possibly  the  loss  of  the  root. 

Numerous  instruments  have  been  devised  for  the  removal  of  this 
enamel ;  among  the  most  efficient  are  those  invented  by  Dr.  Calvin 
S.  Case  and  Dr.  Geo.  M.  Weirich.  Fig.  385  illustrates  Dr.  Case's 
enamel  cleavers.  These  are  so  shaped  that  they  can  be  partially 
rotated   under  the  margin   of  the   gum,   presenting  a   sharp   point 


504  MECHANICAL   DENTISTRY. 

toward  portions  of  the  enamel  that  will  not  easily  clean  off,  with  a 


Fig.  385. 


Fig.  386. 


view  to  fracturing  it  as  the 
diamond  cuts  glass,  breaking 
it  up  into  small  pieces  which 
can  readily  be  detached  and 
the  sides  straightened  and 
smoothed  by  the  broad  blade. 
The  peculiarities  of  shape  are  shown  in  the  enlarged 
cuts. 

The  Wei  rich  cleaver  or  chisel  is  shown  in  Fig. 
386.  With  this  instrument  and  a  few  gentle  blows 
from  the  mallet  the  enamel  is  readily  broken  up  and 
detached.  The  rubber  cushion  in  the  center  of  the 
chisel  takes  up  the  blow,  thus  relieving  the  root 
from  unnecessary  shock.  In  the  accompanying 
illustration  the  instrument  is  shown  in  place  ready 
to  receive  the  blow  from  the  mallet.  It  is  a  well- 
known  fact  that  with  most  of  the  appliances  on 
sale  it  is  difficult  to  properly  remove  the  enamel 
from  the  approximal  surfaces  of  roots,  especially 
where  they  are  very  close.  With  this  instrument,  to  be 
followed  with  the  ordinary  cervical  wall  chisel  or  the  Chase 
cleavers,  the  root  upon  all  sides  can  be  readily  and  properly 
prepared  for  the  reception  of  a  band  or  collar  with  very  little 
discomfort  to  the  patient  or  trouble  to  the  operator. 

3.  After    the    enamel    has    been    thoroughly    removed,    an 
accurate  measurement   of   the  neck   of  the   root   should  be 
secured.     For  this  purpose  Dr.  A.  I.  F.  Buxbaum,  of  Cin- 
cinnati,   has    devised    an    instrument    known    as    Buxbaum's 
dentimeter,   with   which   the  work   can   be   very   satisfactorily   per- 


ARTIFICIAL    CROWNS. 


505 


formed.  It  is  illustrated  in  Fig.  387.  It  is  very  simple  to  adjust 
and  operate,  and  has  the  advantage  over  other  instruments  of  this 
kind,  that,  as  you  do  not  have  to  twist  the  entire  instrument,  the 
wire  does  not  incline  to  slip  off  the  root  or  lacerate  the  gum. 

Dr.  Buxbaum  gives  instructions  for  using  his  dentimeter  as 
follows :  "  Pass  one  end  of  a  soft  wire  through  tube  at  C,  as  shown 
in  Fig.  2  of  accompanying  illustration,  and  wrap  once  around  knob 
D.  Pass  the  other  end  of  wire  through  tube  at  E,  as  shown  in 
Fig.  2,  and  wrap  around  knob  F.  Place  the  loop  H  around  the 
tooth  or  root.  While  unscrewing  the  screw,  by  holding  milled  nut 
B  between  the  thumb  and  forefinger  of  right  hand,  you  must  make 
constant  traction   on  loop   around  the  tooth  by  gently  pulling  on 

Fig.  387. 


barrel  A,  held  between  thumb  and  finger  of  left  hand ;  this  will  give 
a  perfect  twist,  as  shown  in  Fig.  3.  Unfasten  ends  of  wire  from  the 
knobs  D  and  F  and  withdraw  from  dentimeter.  The  result  is 
shown  in  Fig.  4." 

Other  and  simpler  instruments  for  taking  measurements  of  teeth 
or  roots  have  been  devised,  notably  those  by  Dr.  Edward  C.  Kirk, 
and  Dr.  Geo.  M.  Weirich,  of  Philadelphia,  which  are  shown  in 
Fig.  388. 

4.  In  order  to  transfer  this  measurement  accurately  to  the  band- 
ing material,  cut  the  wire  loop  in  the  center  and  spread  the  ends 
in  opposite  directions,  as  shown  in  Fig.  389.  It  is  then  laid  on 
the  piece  of  gold  to  be  used  for  the  band  (which  should  be  22-carat 
and  about  30  gage)  ;  this  should  be  cut  the  exact  length  of  the  ivire, 


5o6 


MECHANICAL   DENTISTRY. 


\u 


and  about  }i  of  an  inch  in  width,  unless  for  special  reasons  it  is 
necessary  to  have  it  wider.     This  small  strip  of 
Fig.  388.  g^   shouicl   now   be   annealed   over   a   lamp   or 

Bunsen  burner,  then  with  round-nosed  pliers  it 
should  be  brought  into  a  circular  form,  and  with 
the  fingers  the  ends  should  be  carefully  pressed 
by  each  other.  This  will  form  a  slight  kink  in 
the  band,  so  that  the  ends,  if  now  gently  drawn 
apart  and  let  go,  will  spring  accurately  together 
ready  for  soldering. 

5.  In  soldering  the  band,  a  corner  of  the  two 
edges  should  be  grasped  with  the  soldering  pliers, 
the  joint  slightly  coated  with  borax,  and  a  small 
piece  of  20-carat  solder  placed  over  it,  on  the  out- 
side of  the  band  (see  Fig.  390).  It 
should  then  be  held  in  the  flame  of  a  FlG-  389< 
Bunsen  burner  until  the  solder  flows, 
at  which  time  it  should  be  instantly 
removed.  With  a  little  experience 
and  care  in  soldering  in  this  way 
(over  a  Bunsen  burner),  it  can  be 
done  more  conveniently,  in  less  time, 
and  with  much  less  danger  of  burn- 
ing the  band,  than  with  the  blowpipe. 

6.  The  band  is  now  ready  to  be  fitted  or  ad- 
justed to  the  root.  If  the  end  of  the  root  is  not 
round,  as  is  usually  the  case,  the  sides  of  the 
band  can  be  flattened  or  otherwise  shaped  with 
slight  pressure  from  the  thumb  and  finger  or 
with  suitable  pliers.  The  upper  border  should 
then  be  trimmed  to  conform  to  the  shape  of  the 
process  or  the  line  of  the  gum  attachment;  in 
many  cases,  unless  the  band  is  greatly  depressed 
or  cut  out  on  the  sides,  it  will  be  found  that  the 
gum  will  be  detached  from  the  sides  of  the  root, 
and  that  the  process  will  be  reached  before  the 
root  is  covered  high  enough  on  the  labial  and 
palatal    surfaces.     Place   the    band    thus    shaped 

ii] >i m  the  root,  and  if  the  measurement  and  each  progressive  stage 


ARTIFICIAL    CROWNS. 


507 


have  been  accurately  performed,  it  will  be  found  to  fit  perfectly. 
Now  press  or  drive  it  up  carefully,  until  the  point  of  attachment 
between  the  soft  tissues  and  the  root  is  reached  (about  Jg  of  an 
inch  bevond  the  gum  margin),  which  is  shown  by  the  slight 
whitening  of  the  gum.  When  this  is  very  marked  upon  any 
side,  the  band  should  be  removed  and  relieved  by  cutting  it  away 
at  that  point,  and  then  readjusted.  A  corundum  wheel  is  now 
gently  passed  over  the  labial  portion  of  the  lower  edge  of  the  band, 
to  level  it  with  the  face  of  the  root  and  to  render  the  band  invisi- 


Fig.  390. 


Fig.  391. 


ble  when  the  crown  is  finished.  In  doing  this  the  wheel  used 
should  be  revolved  toward  the  root,  to  prevent  irritation  of  the  soft 
tissues,  and  at  the  same  time  it  will  turn  the  feather  edge  of  metal 
•over  the  end  of  the  root. 

7.  The  base-plate  is  more  easily  and  quickly  formed.  Cut  a 
piece  of  gold  (34  gage)  of  suitable  length  and  width,  anneal,  and 
then  press  it  against  the  lower  edge  of  the  band  with  the  fingers 
until  it  is  nicely  adapted ;  secure  it  in  this  position  for  soldering  by 
three  or  four  strands  of  wire,  as  shown  in  Fig.  391. 

Now  paint  the  joint  with  borax  dissolved  in  water,  lay 
a  small  piece  of  20-carat  solder  against  the  back  or 
palatal  portion  of  the  band,  on  the  outside,  and  hold  it 
in  the  flame  of  a  Bunsen  burner  until  the  solder  flows, 
which  will  be  seen  to  run  entirely  around  the  band,  uniting  it  with 
the  base-plate  at  every  point.  The  surplus  of  the  base-plate  material 
should,  with  shears  (see  Fig.  392)  and  corundum  stone,  be  trimmed 
•off  flush  with  the  band,  the  two  now  forming  a  complete  cap  for  the 
face  and  sides  of  the  root. 

8.  The  next  step  is  the  preparation  and  adjustment  of  a  pin 
through  the  cap  into  the  root  canal.  The  canal  should  be  enlarged 
toward  the  palatal  side  of  the  root;  this  will  give  more  room  for 
grinding  and  adjusting  the  tooth,  and  at  the  same  time  secure  the 
greatest  attainable  strength  when  the  crown  is  completed. 

The  base-plate  of  the  cap  is  perforated  at  a  point  directly  over 
the  opening  into  the  canal.     This  may  be  done  either  with  a  bur 


;o8 


MECHANICAL   DENTISTRY. 


on  the  dental  engine  or  with  the  plate  punch.     A  pin  of  platinum 
wire.,    Xo.     16    or    17,    standard    gage,    should    now    be    slightly 

Fig.  392. 


Fig.  393. 


tapered  at  the  end  and  passed  through  the  aperture,  and  up  into 
the  root  canal.  The  end  of  the  pin  projecting  below  the  cap  may 
be  marked,  withdrawn,  and  bent  at  a  right  angle,  so  that 
it  will  point  away  from  the  tooth,  that  is,  toward  the  palatal 
surface ;  it  may  then  be  waxed  in,  invested,  and  soldered 
with  the  tooth,  or,  invested  and  soldered  at  this  stage,  and 
the  surplus  of  pin  and  solder  brought  down  flush  with  a 
file  or  stone. 

9.  The  cap  and  pin  should  be  readjusted  to  the  root.  A 
plain  plate  tooth,*  of  suitable  form  and  color,  is  now  ground  and 
fitted  to  the  cap.     The  labio-cervical  edge  of  the  tooth  (a,  Fig.  393), 


*  Many  writers  advise  using  cross-pin  teeth  ;  it  is  self-evident,  however,  that  in 
this  work  straight-pin  teeth  should  be  employed  and  the  cross-pins  avoided 
wherever  possible,  for  the  following  reasons:  (1)  The  position  of  the  pins  weak- 
ens the  body  of  the  tooth.  (2)  Their  position  makes  the  strain  upon  the  tooth 
greater,  as  it  gives  increased  leverage  between  the  pins  and  the  cutting  edge.  (3) 
There  is  more  liability  of  cracking  the  teeth  in  soldering,  on  account  of  so  much 
metal   being  brought   at  one  point. 


ARTIFICIAL    CROWNS.  509 

should  be  so  ground  that  it  will  be  flush  with  the  edge  of  the  band 
and  meet  the  margin  of  the  gum.  It  should  also  be  ground  out 
at  the  center  of  the  base  (&),  so  as  to  form  a  slight  space  just  over 
the  base  of  the  pin. 

The  tooth  is  then  backed  with  either  thin  platinum  or  gold  plate 
(gold  will  give  a  slight  yellow  shade  to  the  tooth,  while  platinum 
will  give  a  bluish  tint).  The  upper  edge  of  the  backing,  brought 
down  thin  with  a  file  or  stone,  should  extend  as  far  as  possible 
under  and  between  the  tooth  and  the  cap,  so  that  the  solder  will 
more  readily  flow  in  and  fill  what  space  there  may  be.  The  incisive 
edge  of  the  backing  should  also  be  brought  slightly  over  the  edge 
of  the  porcelain  (though  it  is  not  so  shown  in  the  accompanying 
illustrations),  this  portion  of  the  tooth  being  previously  beveled 
with  a  fine  corundum  stone.  In  this,  the  possibility  of  breaking  the 
tooth  from  the  force  of  mastication  is  much  diminished. 

10.  A  perfect  joint  and  the  proper  length  and  angle  of  the  tooth 
having  been  secured,  the  pieces,  that  is,  the  tooth,  cap,  and  pin, 
should  now  be  thoroughly  dried  and  then  held  together  in  the 
proper  relationship,  and  secured  in  this  position  by  running  warm 
adhesive  (resin)  wax  over  the  palatal  portion  of  the  tooth,  attaching 
the  backing  to  the  cap.  It  should  then,  before  the  wax  gets  very 
hard,  be  carefully  carried  to  position  upon  the  root,  when  any  cor- 
rection in  the  position  of  the  tooth  can  readily  be  made.  Now  apply 
a  little  cold  water  from  the  syringe  or  on  a  pledget  of  cotton;  this 
will  harden  the  wax,  so  that  the  crown  may  be  removed  without 
changing  the  position  of  the  tooth  upon  the  cap.  It  will  then  be 
ready  to  be  invested  for  soldering. 

A  most  suitable  investment  for  crown-work  is  marble-dust  and 
plaster,  equal  parts,  with  a  small'  quantity  of  fine  asbestos  fiber 
thoroughly  incorporated.  After  the  investment  has  thoroughly 
set,  the  wax  may  be  removed  and  the  surface  of  the  backing  and 
cap  cleansed  by  directing  upon  it  a  small  stream  of  boiling  water. 
The  investment  should  be  cut  away  so  as  to  expose  the  sides  of  the 
backing  and  the  lower  border  of  the  band,  as  illustrated  in  Fig.  394. 
but  every  portion  of  the  porcelain  should  be  protected.  The  case 
should  then  be  at  first  gently  heated  up,  to  drive  off  the  moisture, 
then  transferred  to  the  soldering  block,  when,  with  the  blowpipe, 
more  heat  should  be  applied,  continuously  at  first,  until  the  in- 
vestment and  tooth  are  thoroughlv  and  evenlv  heated  throughout. 


IO 


MECHANICAL   DENTISTRY. 


Gold  solder,  18-carat,  is  then  cut  in  small  pieces  and  placed,  with  a 
little  borax,  over  the  aperture  between  the  backing  of  the  tooth 
and  the  cap.  The  investment  being  now  uniformly  heated,  the 
flame  from  the  blowpipe  should  be  directed  upon  the  solder, 
mostly  in  the  direction  indicated  in  Fig.  394,  when,  if  the  entire 
case  has  been  previously  brought  to  a  red  heat,  the  solder  will 
readily  melt  and  flow  betwen  the  tooth  and  cap.  Additional  solder 
should  now  be  added  and  melted  until  the  proper  contour  of  the 
tooth  is  insured. 

The  tooth  and  investment  should  then  be  placed  in  and  covered 
with  sand,  plaster,  or  some  other  suitable  substance  to  keep  the 
heat  from  radiating  too  rapidly  and  thus  cracking  the  tooth.  It 
should  be  left  so  covered  until  it  is  thoroughly  cool.  We  might 
add  here,  that  it  is  well  to  direct  the  flame  from  the  blowpipe  into 
the  sand  or  other  material  for  a  moment  before  placing  the  tooth 


Fig.   394. 


Fig.   395. 


in.  After  the  tooth  is  thoroughly  cool,  the  investment  may  be 
broken  away,  and  all  oxidation  and  borax  removed  by  placing  it 
for  a  few  minutes  in  the  acid  bath.  The  crown  is  then  ready  to  be 
finished  and  polished.  The  shaping  of  the  solder  can  best  be  done 
with  corundum  stones,  followed  with  hard-rubber  discs,  and  then 
fine  sandpaper  or  cuttlefish  discs,  while  the  polishing  is  accom- 
plished with  brush  and  buff  wheels,  pumice-stone,  whiting,  and 
rouge.     The  completed  crown  in  position  is  shown  in  Fig.  395. 

The  Richmond  Method  Applied  to  Bicuspid  Roots. — The 
capping  of  the  root  is  similar  to  that  already  described ;  the  crown 
will  have  greater  strength,  however,  if  a  portion  of  the  palatal 
section  of  the  natural  crown,  when  strong  enough,  is  retained,  and 
the  band  made  deep  enough  to  cover  it.  One  pin  is  all  that  is 
usually  required,  and  where  there  are  two  distinct  canals,  the 
palatal  should  be  used  to  receive  the  pin ;  thus  greater  strength  is 


ARTIFICIAL    CROWNS. 


511 


secured  at  the  point  where  it  is  most  needed,  and  the  pin  is  so 
located  that  it  will  not  interfere  with  the  grinding  and  adjustment  of 
the  tooth.  The  cap  and  pin  being  in  position,  a  suitable  cuspid 
tooth  or  bicuspid  facing  is  then  ground,  backed,  and  adjusted  to 
represent  the  labial  aspect,  and  then  properly  secured  to  the  cap 
with  adhesive  wax.  The  tooth,  cap,  and  pin  are  then  carefully 
removed,  invested,  and  soldered;  after  which  they  are  again 
placed  upon  the  root,  and  the  occluding  edge  of  the  tooth  is 
ground  clear  of  the  antagonizing  teeth  at  about  the  angle  shown 
at  A,  Fig.  396. 

From  a  suitable  die  or  die-plate  the  cusps  or  occluding  surface 
of  the  tooth  are  swaged  from  22-carat  gold  plate.  These  cusps 
should  then  be  filled  in  with  18-  or  20-carat  plate  or  solder. 
This  is  done  by  cutting  the  gold  into  small  pieces,  and  placing 
them,  with  a  little  borax,  in  the  depressions  of  the  cusps,  all  of 


Fig.   396. 


Fig.    397. 


Fig.    398. 


which  is  held  over  a  Bunsen  burner  until  the  small  pieces  are 
melted,  when  they  will  flow  into  these  depressions  and  fill  them 
level  full.  The  surplus  is  trimmed  away,  the  cusps  ground  and 
fitted  to  the  edge  of  the  porcelain  front,  in  position  to  secure 
proper  occlusion  (Fig.  397),  and  secured  with  wax  as  shown  at  A. 

A  piece  of  thin,  pure  gold  plate  or  mica  is  then  adjusted  on 
each  side  of  the  crown  (B,  Fig.  397),  the  surfaces  of  which,  if  dry 
and  slightly  warm,  will  be  held  in  position  temporarily  by  pressing 
them  gently  against  the  side  of  the  wax.  This  is  all  now  invested 
together  (Fig.  398). 

The  long  ends  of  these  side  pieces,  after  being  invested,  hold 
them  in  position,  as  the  investment  should  be  cut  away  so  as  to 
expose  the  sides  of  the  crown  as  shown  at  A,  Fig.  398.  In  the 
process  of  soldering,  after  the  case  has  been  properly  heated,  the 
small  pieces  of  solder  and  borax  are  placed  in  the  aperture  formed 


512  MECHANICAL    DENTISTRY. 

by  these  sides  of  gold  or  mica  (the  place  formerly  filled  with  wax), 
and  the  flame  from  the  blowpipe  directed  cautiously  against  these 
exposed  sides  (A).  The  solder  will  then  flow,  uniting  the  several 
parts,  when  more  should  be  added  until  the  proper  contour,  with 
perfect  continuity  of  structure,  is  secured.  The  crown  can  be  made 
without  the  gold  or  mica  sides  if  great  care  is  exercised  in  flowing 
the  solder.  There  will  be  more  surplus  solder,  however,  to  be  fin- 
ished off. 

In  finishing,  the  solder  is  brought  to  the  contour  of  a  bicuspid 
tooth  with  corundum  stones  and  sandpaper  discs,  when  it  is  ready 
for  the  polishing  process.  The  finished  crown  is  represented  in 
place  upon  the  root  in  Fig.  399. 

There  are  other  methods  practised,  and  though  some  of  them 
may  not  be  as  artistic  as  the  one  just  described,  they  are  much 
simpler  and  quicker.  For  instance,  the  palatal  cusp  may  be  built 
up  with  several  pieces  of  gold  plate — previously  melted 
_399'  into  the  form  of  balls  and  flattened  out  with  a  hammer. 
The  backing  is  brought  down  and  closely  burnished  over 
the  cutting  edge  of  the  tooth,  which  is  then  waxed  in 
position,  tried  in  the  mouth,  and  invested,  and  when  ready 
to  be  soldered  these  flattened  pieces  of  gold  are  laid  in 
position,  united,  and  filled  in  with  18-carat  solder,  which 
is  also  brought  over  the  backing  to  the  tip  of  the  tooth. 
This  plate  and  solder  are  afterward  brought  to  the  proper  shape 
and  contour  with  the  stones  and  discs. 

Then,  again,  the  palatal  portion  of  the  band  is  extended  down 
so  as  to  nearly  touch  the  antagonizing  tooth.  This  leaves  only  a 
comparatively  small  space  to  be  filled  in  with  solder,  which  is 
afterward  trimmed  and  finished  to  the  form  of  the  crown. 

Or,  a  method  that  the  writer  often  employs  is  to  back  the  tooth, 
grind  off  or  bevel  the  occluding  surface,  and  then  joint  and  adjust 
the  prepared  gold  cusps ;  wax  them  in  position,  invest,  and  flow 
in  sufficient  20-carat  solder  to  hold  them  securely  in  position,  after 
which  the  tooth  may  be  ground,  adjusted,  and  soldered  to  the  cap, 
as  has  been  directed.  One  advantage  of  this  method  is  that  differ- 
ent forms  and  shades  of  bicuspid  facings  may  be  so  prepared — 
with  gold  occluding  surfaces — and  kept  in  stock ;  and,  again,  in 
the  latter  three  methods,  as  may  be  seen,  it  is  only  necessary  to 
invest  the  cap  once  after  adjusting  the  tooth. 


ARTIFICIAL   CROWNS. 


513 


Fig.  401. 


Dr.  Litch's  Method. — The  method  devised  by  Prof.  Wilbur  F. 
Litch  for  forming  collar  crowns  was  first  published  in  the  Dental 
Cosmos  (Vol.  xxv,  p.  449),  and  was  afterward  revised  and  repro- 
duced in  the  "  American  System  of  Dentistry."  In  this  Prof.  Litch 
describes  his  method  as  follows : 

"  The  processes  to  be  described  reduce  destruction  of  tooth 
substance  to  the  minimum.  Instead  of  cutting  the  palatine  wall  of 
the  tooth  down  to  the  gum  margin,  the  greater  portion  of  it  is  care- 
fully- conserved,  its  presence,  while  not  indispensable  to  a  success- 
ful result,  being  in  the  highest  degree  desirable.  How  much  of  this 
portion  of  the  tooth  can  be  retained  will  depend  upon  the  nature  of 
the  occlusion. 

"  In  Fig.  400  the  dotted  line  from  C  to  D  represents  the  point  to 
which  the  tooth  is  cut  away  in  the  older  methods  of  pivoting;  the 
dotted  line  from  A  to  B,  the  line  of  abscission  practised  by  the  writer. 

"  As  will  be  seen  by  reference  to 
Fig.  401,  the  face  of  the  tooth  thus 
prepared  presents  a  gradual  slope 
from  the  palatal  surface  to  the  labio- 
cervical  margin.  At  the  latter  mar- 
gin the  root  should  be  cut  down  with 
suitable  instruments  to  a  point  a  little 
beneath  the  edge  of  the  gum,  in  order 
that  the  porcelain  tooth  in  front  may 
pass  up  under  the  gum  margin,  and 

the  joint  between  the  tooth  and  root  be  concealed.  At  this  point 
tooth  substance  may  be  sacrificed,  as  it  does  not  materially  diminish 
the  strength  of  the  root. 

"  The  several  parts  employed  in  making  the  collar  crown  are  a 
plain  plate  porcelain  tooth  or  facing,  a  platinum-iridium  retaining 
pin,  and  a  backing,  base-plate,  and  collar,  made  either  of  platinum, 
pure  gold,  or  22-carat  gold,  either  metal  being  made  in  thickness 
about  No.  30,  American  gage.  When  platinum  is  used,  coin  gold 
or  20-carat  gold,  alloyed  with  copper  or  silver  only,  should  be  em- 
ployed as  a  solder  and  covering.  Twenty-carat  gold  may  be  used 
as  a  solder  when  pure  gold  is  employed,  while  18-carat  gold  will- 
solder  the  22-carat  plate. 

"  In  shaping  the  pulp  canal  for  the  reception  of  the  retaining 
pin  care  should  be  taken  not  to  weaken  the  root  by  an  unnecessary 

33 


A-' 


5J4 


MECHANICAL   DENTISTRY. 


enlargement  of  the  caliber  of  the  canal.  The  platinuni-iridium 
pin  need  not  be  more  than  No.  14  American  gage  in  thickness  at 
its  point  of  greatest  diameter,  near  the  free  surface  of  the  root, 
where  all  the  strain,  if  any,  falls ;  from  this  point  it  should  be  made 
a  gentle  taper  corresponding  to  the  natural  shape  of  the  space  it  is 
to  occupy.     Half  an  inch  in  length  is  ample ;  even  less  will  serve. 

"  The  retaining  pin  being  shaped  and  adjusted  on  the  root,  care 
being  taken  to  leave  an  excess  in  length  at  the  free  end  for  con- 
venience in  subsequent  manipulations,  the  next  step  in  the  process 
is  the  making  of  the  base-plate  and  its  attachment  to  the  pin. 
A  strip  of  platinum  or  gold  of  suitable  size  is  pressed  upon  the  face 
of  the  root  with  broad-pointed,  serrated  instruments  until  it  is  in 
close  adaptation  to  the  surface  at  every  point.  This  base-plate  is 
allowed  to  project  beyond  and  overhang  the  palatine  portion  of  the 
root,  but  should  not  come  quite  to  the  labial  edge. 

"  Adaptation  being  secured,  an  opening  is  made  in  the  base-plate 
where  it  covers  the  pulp  canal,  through  which  opening  the  retain- 
ing pin  may  be  pressed  up  into  position  in  the  root.  Pin  and  base- 
plate are  then  removed  from  the  mouth,  dried,  and  cemented  with 
a  brittle  resinous  cement,  and  then,  while  the  cement  is  still  plastic 
and  yielding  from  heat,  placed  again  in  position  in  and  upon 
the  tooth,  and  perfect  adaptation  secured.  While  still  in  position 
in  the  mouth,  throw  upon  the  cement  a  stream  of  very  cold  water, 
so  that  it  may  be  made  brittle  and  incapable  of  bending.  Then 
remove  from  the  mouth  and  invest  in  a  mixture  of  equal  parts  of 
plaster  and  pulverized  marble,  with  enough  water  to  make  a  thick 
paste.  After  the  investment  has  set,  solder  the  retaining  pin  and 
the  base-plate  together. 

''  To  make  the  collar,  a  somewhat  crescent-shaped  piece  of 
platinum  or  gold  of  suitable  size  is  prepared  and  pressed  into 
shape  upon  the  palatine  and  palatoproximal  face  of  the  tooth; 
little  slits  may  be  cut  in  the  collar  with  a  delicate  pair  of  scissors, 
to  make  easier  this  adaptation.  Care  should  be  taken  not  to  push 
the  collar  up  under  the  gum  at  any  point,  provided  the  palatine 
wall  of  the  tooth,  which  had  been  allowed  to  remain  standing,  is  at 
all  ample  in  height — say  X  of  an  inch ;  if  less  than  this  the  collar 
may  pass  under  the  gum  for  a  short  distance,  as  will  be  shown 
subsequently.  In  the  average  case  this  collar  will  not  quite  en- 
circle one-half  the  tooth. 


ARTIFICIAL    CROWNS.  5  I  5> 

i  "  Fig.  402  shows  the  collar  curved  to  the  outline  of  the  gum 
margin  and  shaped  to  the  contour  of  the  palatoproximal  wall  of 
the  tooth.  At  G  the  slits  are  cut  in  the  platinum  to  allow  over- 
lapping in  shaping  to  contour. 

"  In  order  to  strengthen  the  collar  and  facilitate  its  attachment  to 
the  base-plate  cut  a  series  of  slits  in  -that  portion  of  the  base-plate 
which  has  been  made  to  project  beyond  the  palatine  wall  of  the 
tooth,  and  the  base-plate,  with  its  now  attached  pin, 
being  placed  with  the  collar  in  position  in  and  upon 
the  tooth,  the  little  strips  of  metal  into  which  the 
overhanging  edge  of  the  base-plate  has  been  cut  are 
pressed,  one  after  the  other,  down  upon  the  collar 
and  carefully  molded  to  its  surface,  so  that  the  collar 
will  no  longer  consist  of  a  single  thickness  of  metal,  but  will  be 
reinforced  by  these  additional  thicknesses  of  base-plate  thus  pressed 
upon  it. 

"  Fig.  403  shows  this  quite  perfectly :  H  is  the  free  end  of  the 
retaining  pin,  which  is  to  be  cut  off  when  the  porcelain  tooth  is 
mounted.  I  is  the  base-plate,  with  its  overhanging  palatine 
margin  cut  into  strips,  J,  which  are  being  pressed  down  upon  the 

collar,   F,   by  the  broad-surfaced  and   serrated 
Fig.  403.  . 

instrument,  K.  This  being  accomplished,  re- 
move the  several  pieces  from  the  mouth,  care- 
fully cement  the  collar  in  its  proper  position 
relative  to  the  base-plate,  which  will  now  form 
a  sort  of  matrix  for  it,  again  place  in  the  mouth, 
readjust,  harden  the  cement,  remove  from  the 
mouth,  invest  as  before,  and  solder  the  collar 
and  base-plate  together,  using  a  considerable 
Pressing  the  base-plate  f      w      f      covering,  so  that  the  collar 

over   the    collar.  fe 

may    be     still     further    strengthened     and    its 
surface  be  made  uniform. 

"  In  cementing  the  collar  to  the  base-plate  one  precaution  is 
imperative — namely,  not  to  allow  a  film  of  cement  to  get  between 
the  collar  and  the  tooth.  If  this  is  done  and  the  investment  poured 
in  upon  this  film  of  cement,  the  latter  will  immediately  burn  out  as 
soon  as  heat  is  applied,  leaving  a  space  between  the  collar  and  the 
investment  into  which  the  gold  solder  will  flow,  and  thus  interfere 


5  l6  MECHANICAL    DENTISTRY. 

with  that  perfect  adaptation  of  the  appliance  to  the  tooth  which  is 
necessary  to  a  successful  result. 

"  The  mounting  of  the  facing  next  demands  attention.  As 
already  stated,  a  plain  plate  porcelain  tooth  is  used.  This  must 
have  what  are  technically  known  as  cross-pins;  that  is,  pins  placed 
at  right  angles  with  the  long  axis  of  the  tooth.  They  must  also 
be  placed  well  up  toward  the  cutting  edge.  If  they  are  too  near 
the  neck  they  will  inevitably  be  cut  out  in  fitting  the  tooth  to  the 
slope  of  the  base-plate  on  which  it  must  be  mounted. 

"  Fig.  404  shows  the  form  of  the  facing  and  indicates  the  slope 
given  it  in  fitting.  The  fitting  process  does  not  differ  from  that 
ordinarily  employed  with  porcelain  teeth ;  an  impression  may  be 
taken  and  the  work  done  on  a  cast,  or  the  facing  may  be  fitted  to 
the  mouth.  In  either  case  it  is  in  the  mouth  that  the  finer  and  final 
adjustments  as  to  height,  contour,  alignment,  etc.,  must  be  perfected. 
"  This  being  done  and  the  facing  backed,  tooth 
and  base-plate  are  cemented  together,  restored  to  the 
mouth,  finally  adjusted,  removed,  and  soldered  as  be- 
fore, as  much  gold  being  flowed  into  the  angle  be- 
tween the  backing  and  the  base-plate  as  occlusion 

Shape  of  porce-      ^  ^ 

lain  facing.  ,  .  .      .  .  . 

'  This    artificial    crown,    being    properly    finished 

and  cemented  into  position  in  and  upon  the  tooth,  makes  what 
the  writer,  from  several  years'  experience  in  its  use  in  a  large 
number  of  cases,  has  found  to  be  an  appliance  which  will  remain 
for  an  indefinite  period  without  the  slightest  deviation  from  posi- 
tion and  alignment,  and  which  in  many  respects  is  almost  as 
strong  as  the  natural  tooth,  because  its  point  of  greatest  resist- 
ance to  pressure  is  placed  where  Nature  anchors  her  enamel 
walls — namely,  upon  the  outside  and  not  upon  the  inside  of  the 
walls  of  dentine;  so  that  in  the  act  of  occlusion  the  force  applied 
by  the  lower  incisors  as  they  come  up  in  position  inside  the  upper 
incisors  falls  upon  the  whole  thickness  of  the  root  through  the  collar, 
and  not  upon  less  than  half  its  thickness  through  a  centrally 
anchored  pin — a  pin,  too,  prolonged  into  a  lever  of  enormous  power 
by  its  attachment  to  the  porcelain  tooth. 

"  In  this  respect  there  is  a  manifest  weakness  in  all  methods  of 
mounting  artificial  crowns  which  depend  for  their  stability  solely 
upon   the    central   pin.     Ultimate    failure   through    splitting   of   the 


ARTIFICIAL    CROWNS. 


517 


Fig.  405. 


F 1  0  lMh-H 


root  is  the  frequent  result,  and  the  larger  and  stronger  and  more 
deeply  anchored  the  pin  the  more  certain  this  result,  because  a 
large  pin  necessitates  a  large  opening  for  its  reception,  and  a 
corresponding  weakening  of  the  root,  upon  which  the  strain  must 
ultimately  fall :  the  lever  is  strengthened  and  the  point  of  resistance 
weakened. 

"  The  only  safety  for  the  usual  form  of  pivot  tooth  is,  either 
that  the  occlusion  shall  be  slight,  the  root  very  strong,  or  the 
pivot  very  flexible  or  elastic.  This  elasticity  of  the  old  hickory 
pivot  was  one  of  its  chief  excellences :  roots  were  much  less 
likely  to  split  than  with  a  rigid,  unyielding  metallic 
pin.  In  cuspids  or  incisors,  however,  metallic  pins, 
unless  enormously  large,  or  thickly  packed  around 
the  amalgam,  will  very  often  bend  outward,  thus 
allowing  a  slight  displacement  forward  of  the  arti- 
ficial crown,  and  to  that  extent  relieving  the  root 
from  strain. 

"  Fig.  405  gives  a  sectional  view  of  the  collar 
crown  in  position,  the  lower  incisor  being  in  occlu- 
sion. L  is  the  porcelain  facing.  H  is  the  pin  at- 
tached to  I,  the  base-plate.  M  is  the  backing  and 
solder.  N  is  the  lower  incisor,  and  F  the  collar. 
It  is  clearly  evident  that  here  the  force  of  occlusion 
falls  upon  the  palatine  wall  of  the  natural  tooth  at 
O  through  the  collar  F,  and  not  upon  the  pin  at  the 
point  of  its  attachment  to  the  base-plate  H,  and 
through  the  pin  upon  the  thin  outer  shell  of  the 
root. 

"  In  cases  frequently  met  with,  where  the  entire 
crown  of  the  tooth  has  been  removed,  the  collar,  as  before  described, 
can  be  adapted  to  the  palatine  face  of  the  root,  provided  the  latter 
be  not  decayed  away  up  to  the  alveolar  margin.  Usually,  however, 
there  is  a  considerable  space  between  the  free  edge  of  the  root  and 
the  alveolus,  and  here,  running  up  to  the  alveolus,  the  collar  must 
be  placed. 

"  The  dotted  line  E  in  Fig.  401  indicates  a  collar  so  placed. 
All  the  steps  in  the  process  are  essentially  the  same  as  before 
described.  Adapting  the  collar  to  the  surface  of  the  root  beneath 
the  gum  is  somewhat  painful,  but  not  excessively  so,   and  in  the 


Sectional  view  of 
collar  crown  in 
position,  the 
lower  incisor 
in  occlusion. 


518  MECHANICAL   DENTISTRY. 

wearing  the  irritation  caused  by  its  presence  is  very  slight  and 
transient  in  character,  assuming,  of  course,  that  care  has  been  taken 
to  leave  upon  it  a  smooth,  thin,  and  well-polished  edge. 

"  The  objection  may  be  urged  that  this  form  of  crown  resists 
pressure  only  in  one  direction,  from  within  outward,  and  does  not 
provide  for  lateral  pressure  or  pressure  from  the  front.  As  a  rule, 
the  latter  can  occur  with  any  force  only  as  the  result  of  accident, 
while  if  the  crowned  tooth  is  in  normal  relation  with  its  fellows, 
and  the  artificial  crown  be  closely  fitted  between  them,  they  will 
fully  sustain  lateral  force. 

"  Where  such  lateral  support  is  wanting  through  isolation  of  the 
tooth,  the  collar  must  be  extended  into  a  ring  or  ferrule  completely 
encircling  and  grasping  the  root,  and  thus  affording  support  on  all 
sides.  The  ring,  however,  is  more  troublesome  to  make  and  more 
painful  to  apply,  and  generally  shows  a  line  of  gold  in  front.  In 
the  average  case  the  simple  collar  gives  all  requisite  strength. 

"  In  mounting  crowns  upon  bicuspid  and  molar  roots,  however, 
the  ferrule  principle  is  often  essential  to  stability;  especially  is  this 
true  of  lower  bicuspids  and  molars,  as  here  the  forces  applied  in 
mastication  are  as  erratic  in  direction  as  they  are  powerful  in  char- 
acter, and  the  root  must  be  guarded  at  every  point  against  their 
violence. 

In  fixing  in  position  the  artificial  crowns  just  described,  the 
writer  prefers  to  use  a  gutta-percha  cement  adhesive  in  character, 
which  will  not  strip  from  the  pin  when  the  crown  is  forced  into 
position. 

"  The  apical  foramen  is  closed,  the  pulp  canal  grooved  and 
thoroughly  dried,  the  central  pin  is  barbed,  and  the  pin  and  inside 
of  the  collar  and  under  surface  of  the  base-plate  are  thickly  coated 
with  the  gutta-percha ;  the  entire  appliance  is  then  heated  to  a 
temperature  sufficient  to  thoroughly  soften  the  gutta-percha,  and 
firmly  pressed  up  into  position ;  the  excess  of  gutta-percha  will 
ooze  out  at  all  free  margins,  and  may  be  subsequently  removed 
with  suitable  instruments. 

"  A  good  gutta-percha  cement  will  hold  firmly  in  a  great  majority 
of  cases,  but  when,  as  in  a  small  lateral  incisor,  the  retaining  pin 
is  necessarily  small  and  short  and  the  collar  not  as  ample  as  could 
be  desired,  an  oxyphosphate  cement,  mixed  thin,  will  be  found  to 
give  greater  stability.     When  this  cement  is  used,  however,  it  will 


ARTIFICIAL    CROWNS. 


519 


be  found  very  difficult  to  detach  the  artificial  crown  from  the  root, 
should  it  for  any  reason  become  necessary  to  do  so;  whereas  a 
little  heat  will  quickly  soften  a  gutta-percha  packing  and  permit 
the  entire  appliance  to  be  withdrawn  without  difficulty." 

As  a  modification  of  the  manner  of  constructing  the  collar,  Dr. 
Theodore  F.  Chupein  contributes  the  following  to  the  Dental  Cos- 
mos: 

"  After  the  root  face  has  been  dressed  down  as  shown  in  Fig. 
401,  a  piece  of  pure  gold  plate  of  No.  30  gage  is  cut  as  shown  in 
Fig.  406.  This  is  bent  around  the  root,  as  shown  in  Fig.  407,  the 
wide  part  resting  against  its  palatal  aspect,  while  the  ends  are  seized 
with  a  pair  of  narrow-beaked,  flat-nosed  pliers  at  the  labial  aspect. 
While  thus  held,  the  band  may  be  burnished  to  fit  accurately 
against  the  approximal  and  palatal  parts  of  the  root.  This  done,  it 
is  removed  and  the  ends  soldered  together,  as  shown  in  Fig.  408. 

Fig.  406. 


Fig.  407.         Fig. 


Fig.  409.  Fig.  410.         Fig.  411. 


This  band  is  then  replaced  on  the  root,  and,  as  it  hugs  the  root 
snugly,  any  of  the  edges  which  may  be  higher  than  the  face  of  the 
root  may  be  ground  down  even  with  a  corundum  stump  wheel. 
It  is  again  removed  from  the  root  and  laid  on  a  piece  of  pure  gold 
plate  of  the  same  thickness,  to  which  it  is  soldered,  as  in  Fig.  409. 
The  overhanging  edges  of  the  plate,  as  soldered  to  the  collar,  are 
now  dressed  down  even  with  the  collar,  and  the  forward  part  of 
the  collar  filed  or  ground  away  from  the  plate,  as  shown  in  Fig. 
410.  A  hole  is  now  drilled  or  punched  through  the  face-plate  to 
receive  the  dowel,  which  passes  through  it  into  the  root.  The 
under  part  of  the  face-plate  at  the  hole  should  be  well  countersunk, 
so  that  the  solder  that  binds  the  dowel  to  the  face-plate  may  creep 
through  and  hold  the  dowel  on  its  under  surface.  The  face-plate 
and  collar,  as  shown  at  Fig.  410,  are  placed  on  the  root  and  bur- 
nished down  to  fit  accurately  at  all  points.     A  slight  smearing  of 


520  MECHANICAL   DENTISTRY. 

cement  is  placed  over  the  dowel  hole,  so  as  to  fill  the  countersink, 
and  the  dowel  passed  through  and  secured  to  the  face-plate  with 
more  cement.  Before  this  hardens  it  is  placed  on  the  root  in  its 
proper  position,  after  which  the  cement  is  chilled  by  a  stream  of 
cold  water,  when  it  is  removed,  invested,  and  soldered.  Fig.  411 
shows  the  collar,  face-plate,  and  dowel  complete.  This  being  accom- 
plished, the  face-plate  is  slightly  reduced  on  its  labial  aspect,  so  as 
to  expose  the  root  against  which  the  porcelain  facing  is  to  rest.  The 
protruding  part  of  the  dowel  is  now  cut  off  level  with  the  face-plate, 
and  the  porcelain  tooth  fitted  to  it.  This  part  of  the  operation  does 
not  differ  from  that  indicated  by  Prof.  Litch,  and  therefore  need  not 
be  repeated  here. 

"  The  operation  as  set  forth  consumes  much  less  time,  is  less 
tedious,  does  not  demand  the  nice  manipulative  ability  of  the  other, 
and  is  more  certain  in  its  results." 

Dr.  Knapp's  Process. — No  individual  method  has,  perhaps, 
more  immediately  and  generally  commanded  the  approval  and 
commendation  of  expert  and  discriminating  operators  than  the  one 
brought  to  the  notice  of  the  profession  by  Dr.  J.  Rollo  Knapp,  of 
New  Orleans,  La.  Omitting  some  judicious  and  pertinent  general 
reflections  on  the  subject  (see  Dental  Cosmos,  of  February,  1887), 
all  that  relates  to  practical  details  in  his  methods  of  procedure  is 
here  reproduced : 

"  The  collar  being  removed,  its  gingival  border  must  be  carefully 
filed  so  as  to  adjust  it  exactly  to  the  various  inequalities  existing 
in  the  borders  of  the  alveolar  process  and  its  investing  gum.  The 
other  border  should  then  be  evenly  filed  down  so  as  to  reduce  the 
collar  to  the  requisite  narrowness.  A  piece  of  pure  gold  plate,  gage 
34,  is  now  to  be  soldered  upon  this  latter  border  so  as  to  convert 
the  collar  into  a  cap  for  the  root.  This  cap  must  have  pierced  in 
it  such  an  aperture  as  will  conform  to  the  configuration  of  the  pin 
or  dowel  best  suited  to  the  particular  case  in  hand.  Cap  and  pin 
waxed  together,  should  then  be  tried  in  the  mouth,  carefully  removed, 
invested  in  calcined  marble-dust  and  plaster,  and  soldered.  Being 
again  placed  upon  the  root,  an  impression  of  it  should  be  taken,  as 
well  as  of  the  two  approximal  teeth." 

Small  trays  especially  made  for  the  purpose  (Figs.  412  and  413), 
will  be  found  very  convenient  for  taking  impressions  for  crown- 
work.     Plaster  or  modeling  composition  can  be  used  in  doing  this. 


ARTIFICIAL    CROWNS. 


521 


Upon  its  being  ascertained  that  the  cap,  with  pin  attached,  is  in  its 
proper  position  in  the  impression,  a  plaster  cast  can  be  obtained, 
which,  with  a  cast  of  the  occluding  teeth,  should  be  placed  in  an 
articulator. 

While    the    writer   believes    it    to    be    the    most    accurate,    when 
making  single  crowns,  to  grind  and  adjust  the  tooth  in  the  mouth, 


Fig.  412. 


it  frequently  happens,  from  lack  of  time  or  other -reasons,  that  it  is 
not  practicable;  then  the  impression  should  be  taken  as  directed. 

From  this  point  succeeding  steps  will  differ  according  to  the 
character  of  crown  to  be  inserted.  If  it  be  an  incisor,  which  is  to 
have  a  porcelain  front,  a  plain  plate  tooth  of  suitable  size,  shape, 
and  shade  should  be  backed  with  pure  gold,  ground  to  position 
upon  the  anterior  portion  of  the  cap,  and  united  to  it  by  adhesive 

Fig.  413. 


wax.  Sufficient  wax  should  be  used  to  perfectly  restore  the  con- 
tour and  to  produce  the  most  accurate  knuckling  or  adjustment  of 
the  approximal  surfaces  of  the  teeth.  Too  much  stress  cannot 
be  laid  upon  this  latter  point — one  not  usually  attended  to.  Yet 
all  the  reasons  for  observing  it  in  all  other  kinds  of  contour  work 
are  no  less  potent  here.     In  this  procedure  pure  gold  of  34  gage 


522  MECHANICAL   DENTISTRY. 

should  be  made  to  completely  envelop  the  sides  and  incisive 
portion  of  the  wax,  including  the  edges  of  the  backing  and  con- 
tiguous portions  of  the  cap.  All  should  now  be  invested,  the  wax 
removed  by  boiling  water,  drying  effected  by  a  gentle  heat,  and 
the  resulting  golden  pocket  filled  with  20-carat  solder.  The  solder, 
previously  cut  in  small  squares,  is  to  be  dropped  into  the  mouth 
of  the  mold,  and  sprinkled  with  a  very  little  powdered  borax — re- 
peating this  process  with  the  left  hand  as  fast  as  the  solder  is 
melted  under  the  blowpipe  while  held  in  the  right  hand  until  the 
mold  is  quite  filled.  To  accomplish  this  in  the  best  manner  the 
flame  of  the  blowpipe  should  be  quite  intense,  but  at  the  same  time 
exceedingly  small. 

The  small  and  deep  mold  formed  by  the  gold  shell  enveloped  in 
the  marble  and  plaster  matrix  has  a  very  narrow  opening,  which 
renders  necessary  an  intense  heat,  capable  of  concentration  upon 
and  easy  application  to  the  innermost  recesses  of  the  mold,  which 
is  to  be  filled  with  molten  gold.  An  oxyhydrogen  blowpipe*  was 
therefore  constructed  to  utilize  the  condensed  nitrous  oxid  gas  in 
combination  with  common  illuminating  gas  for  the  production  of  a 
mixture  which  is  conducted  through  a  thin  rubber  tube  of  }i  of  an 
inch  bore  to  a  very  small  blowpipe,  which  emits  a  steady  flow  of 
constantly  ignited  gas  in  the  form  of  a  pointed  pencil  about  ]/2 
of  an  inch  in  length  by  ]/\  of  an  inch  at  its  greatest  diameter. 
With  this  blowpipe  in  hand,  the  plaster  matrix  may  be  speedily 
heated  by  playing  the  stream  of  fire  over  its  surface  until  the  mass 
is  aglow,  when  the  point  of  the  flame  is  thrown  into  the  mold  by 
rapid  thrusts  until  the  solder  melts  like  wax  and  fills  every  part  of 
the  mold  with  liquid  gold.  From  the  first  application  of  the  flame 
to  the  previously  dried  and  warmed  matrix,  there  is  usually  no 
more  than  ten  minutes  consumed  in  bringing  the  solder  to  the  fus- 
ing-point  and  completing  the  cast  of  gold  in  the  little  mold.  It 
would  seem  that  by  such  means  only  can  the  requisite  heat  be 
obtained,  directed,  and  controlled  with  the  sensitiveness  of  adjust- 
ment that  admits  of  the  20-carat  solder  being  melted  in,  yet  with- 
out destruction  of,  the  thin  gold  crucible  within  the  matrix.  After 
cooling,  removing  investient,  and  boiling  in  acid,  superfluous  solder 
can  best  and  most  expeditiously  be  removed  by  corundum  wheels 


*  See  page  45,  Fig.  20. 


ARTIFICIAL    CROWNS. 


523 


on  the  engine.  Care  should  be  taken  not  to  cut  away  the  gold 
forming  the  approximal  knuckling,  and  to  artistically  carve  the 
palatal  portion. 

Fig.  414  represents  a  band  of  collar  gold,  22  carats  fine,  28  gage; 
Fig.  415,  a  soldered  collar  or  ferrule  made  from  it;  Fig.  416,  a 
square  gold  pin,  20  carats  fine;  Fig.  417,  a  plate  of  pure  gold,  34 
gage,  for  a  cap;  Fig.  418,  the  collar,  cap,  and  pin  duly  invested. 
Fig.  419  represents  the  collar,  cap,  and  pin  soldered  together  with 
20-carat  solder;  Fig.  420,  a  lateral  incisor  plate  tooth,  backed  with 
pure  gold,  28  gage,  ground  to  the  anterior  portion  of  the  cap, 
fastened  to  it  with  wax,  contoured  to  represent  a  natural  incisor, 
the  approximal  sides  as  well  as  incisive  portion  of  which,  together 
with  the  edges  of  the  gold  backing  and  contiguous  parts  of  the 
cap,  all  enveloped  in  pure  gold,  34  gage.     Fig.  421  represents  the 


Fig.  414. 


Fig.  415. 


Fig.  416. 


Fig.  417. 


Fig.  418. 


Fig.  419. 


same,  invested  in  calcined  marble-dust  and  plaster,  the  wax  removed, 
disclosing  the  golden  pocket  ready  for  the  reception  of  the  solder. 
Fig.  422  shows  the  crown  after  the  soldering  has  been  effected ;  Fig. 
423,  the  lateral  incisor  crown  divested  of  superfluous  solder  and 
completely  finished. 

In  constructing  a  cuspid,  its  natural  palatal  characteristics  should 
be  as  accurately  reproduced  as  practicable,  Figs.  424,  425,  426,  427, 
and  428.  The  formation  of  a  porcelain-faced  bicuspid  is  similar  to 
that  which  has  just  been  detailed,  up  to  the  soldering  of  the  backed 
tooth  to  the  cap,  Fig.  429.  The  subsequent  stages,  however,  are 
very  different.  The  perfect  configuration  of  a  bicuspid  should  be 
reproduced  in  wax,  aptness  of  occlusion  and  knuckling  being  care- 
fully attended  to,"  Fig.  430.  In  this  condition  the  crown  should  be 
placed  in  a  small  ring,  such  as  is  shown  in  Fig.  431,  first  set  with 
wax  in   the   desired   position,   and   then   secured   there   by   plaster. 


5^4 


MECHANICAL   DENTISTRY. 


The  exposed  portion  of  the  crown  and  surrounding-  plaster  should 
then  be  coated  with  sandarac  varnish  and  molded  in  marble-dust 
and  glycerin,  contained  in  a  corresponding  annular  section,  Fig. 
432.  Over  this  is  to  be  placed  a  conical  tube,  such  as  is  repre- 
sented in  Fig.  433,  and  into  which  molten  zinc  is  to  be  poured. 


Fig.  420.         Fig.   421. 


Fig.  422. 


Fig.  423. 


Fig.  424. 


Fig.  425. 


Fig.  426.         Fig.  427.         Fig.  428.         Fig.  429.         Fig.  430.  Fig.  431. 


Fig.   432. 


Fig.   433. 


Fig.   434. 


Fig.   43S- 


Fig.  436. 


Fig.  437. 


With  the  die,  Fig.  434,  thus  cast,  in  accurately  reproducing  the 
natural  cusps  and  sulci,  there  can  be  obtained  with  pure  gold  plate, 
34  gage,  a  perfect  counterpart  of  the  grinding  surface  of  a  bicuspid 
crown,  Fig.  435.  The  palatal  cavity  of  the  impression  thus  made 
in  the  plate  must  now  be  filled  with  gold   solder,   20  carats  fine, 


ARTIFICIAL    CROWNS. 


525 


after  which  the  piece  must  be  finished  up  by  any  requisite  trim- 
ming-. Care  should  be  taken  to  leave  the  palatal  cusp  entire,  and 
just  enough  of  the  buccal  or  external  cusp  to  combine  with  the 
porcelain  face  in  the  formation  of  a  proper  occluding  surface,  Fig. 
436.     From  the  model,  as  represented  in  Fig.  430,   sufficient  wax 


Fig.    438.         Fig.    439.     Fig.    440.  Fig.    441. 


Fig.    442.  Fig.    444. 


must  now  be  displaced  to  permit  of  the  prepared  gold  cusps  assum- 
ing their  proper  position,  and  the  approximal  surfaces  remaining 
in  the  wax  then  enveloped  with  pure  gold,  34  gage.  The  palatal 
portion  of  the  collar  must  be  protected  with  a  strip  of  pure  gold, 
28  gage,  Jg  of  an  inch  in  width.  All  is  now  ready  to  be  invested, 
Fig.  437.     After  removal  of  the  wax,  through  the  palatal  aperture 


Fig.   445. 


Fig.   446. 


Fig.  447. 


Fig.   449. 


Fig.   450. 


remaining,  the  internal  walls  of  gold  will  be  disclosed,  Fig.  438. 
By  careful  manipulation  with  the  small  and  intense  blowpipe  flame 
before  mentioned,  20-carat  solder  can  be  so  flowed  in  as  to  make  a 
solid  golden  mass,  from  which  can  be  readily  shaped  a  perfect  bicus- 
pid, Fig.  439. 


526  MECHANICAL    DENTISTRY. 

In  the  construction  of  an  all-gold  bicuspid  crown  some  of  the 
steps  differ  from  those  just  described.  Upon  the  cap  are  dropped 
several  beads  of  wax.  From  this  shapeless  mass  is  carved  a  per- 
fect bicuspid.  Fig-.  440.  A  die  is  then  obtained,  Fig.  441.  after  the 
manner  just  detailed.  A  grinding  surface  is  swaged  in  pure  gold, 
Fig.  442.  and  the  cusps  are  filled  with  20-carat  solder,  Fig.  443,  and 
placed  in  proper  position  upon  the  wax  tooth.  A  piece  of  pure 
gold  plate,  slit  at  the  edges  for  facilitating  adjustment,  should  now 
be  made  to  cover  about  two-thirds  of  the  yet  exposed  border  of 
wax.  Fig.  444.  After  being  invested,  and  the  wax  removed  by  hot 
water,  a  suitable  aperture  is  left  for  soldering,  Fig.  445.  The  result- 
ing completed  bicuspid,  true  to  nature,  is  seen  in  Fig.  446.  The 
descriptions  just  given  answer  for  all-gold  molars,  Figs.  447,  448, 
449,  and  450. 

In  carving  the  cusps  and  sulci,  and  in  otherwise  modeling  the 
gold  parts  of  the  crowns,  small  engine  corundum  wheels  and 
points,  varying  from  coarse  to  fine,  and  barely  moistened,  to  insure 
accuracy  and  delicacy  of  touch,  are  preferable  to  files  or  any  form 
of  steel  instruments.  The  smoothing  and  polishing  is  done  with 
wet  felt  wheels,  fine  pumice,  pulverized  silex,  moose-hide  points  with 
chalk,  brush  wheels  and  whiting,  and  finally  with  rouge.  It  is  a 
matter  of  much  importance  that  great  care  should  be  exercised  in 
the  preparation  of  the  gold  used.  The  solder  should  be  uniform,, 
flow  easily,  and  conform  well  in  color  to  the  work  in  hand. 

Dr.  Shields'  System. — The  following  methods,  first  published 
in  the  Dental  Cosmos,  are  contributed  by  Drs.  N.  T.  and  L.  N. 
Shields.  "  The  points  in  this  work  to  which  we  desire  to  direct  atten- 
tion are  its  permanency,  absolute  cleanliness,  and  artistic  beauty 
By  the  methods  herein  described  the  crowns  are  constructed  upon 
anatomical  lines,  larger  at  the  grinding  and  cutting  surfaces,  so  as 
to  admit  of  thorough  mastication  of  food  without  injury  to  the 
gums.  The  ordinary  shell  crowns  are  positively  wrong  in  shape 
and  construction,  because  the  normal  crown  has  a  larger  diameter 
than  the  neck  of  the  tooth,  therefore  a  band  made  to  fit  the  crown 
of  a  tooth  tightly  will  be  tod  large  at  the  neck.  This  will  neces- 
sarily  leave  a  space  for  the  lodging  for  food  debris,  although  it  may 
go  under  the  gum,  will  make  the  gum  present  a  very  unnatural', 
appearance,  will  make  the  gold  tooth  altogether  unnatural  in  con- 
struction, and  the  result,  after  a  very  few  years,  will  be  a  mass  of 


ARTIFICIAL    CROWNS. 


527 


Fig.  451.     Fig.  452.     Fig.  453. 


decay  under  the  shell  crown,  which  makes  it  not  only  a  temporary 
operation,  but  a  constitutionally  as  well  as  a  locally  injurious  one. 

"  The  enamel  widens  or  becomes  thicker  the  nearer  it  approaches 
the  grinding  and  cutting  surfaces,  and  in  order  to  get  a  perfect 
junction  of  the  collar  crown  and  the  neck  of  the  tooth  we  must 
remove  all  enamel."  Their  procedure  is  as  follows :  First  destroy 
the  vitality  of  the  pulp,  then  extract  all  of  it  with  Donaldson's 
nerve  canal  cleansers.  With  a  little  patience  and  using  No.  5  all 
fine,  and  for  every  sitting  a  new  cleanser,  every  particle  should  be 
removed  from  the  roots,  when  they  should  be  perfectly  filled  to 
their  respective  apices.  This  done,  the  whole  crown  is  cut  off 
almost  even  with  the  gum;  there  will  still  be  a  thin  portion  of  the 
enamel  left  surrounding  the  root,  and  this  can  easily  be  removed 
by  using  the  No.  2  and  No.  3  scalers  made  by  the  S.  S.  White 
Dental  Mfg.  Co.  (See  Figs.  451  and 
452.)  This  done,  shape  the  root  for  a 
solid  all-gold  crown,  as  shown  in  Fig. 
453.  The  procedure  in  the  case  of  por- 
celain faced  crowns  will  be  described 
later. 

Around  this  conically  shaped  root 
(the  removal  of  the  enamel  alone  will 
generally  shape  it  sufficiently)  fit  a 
22-carat  gold  band  so  as  to  come  in 
contact  with  all  parts  of  the  conical 

portion  of  the  root,  which,  when  made,  naturally  gives  a  conical 
band.  To  make  this  band,  first  make  a  tin-foil  model,  as  seen  in 
Fig.  454;  this  causes  less  pain  to  the  patient.  From  this  an  absolute 
shape  in  gold  is  obtained  more  quickly,  and  a  saving  of  gold  results. 
This  band  is  soldered  with  22-carat  solder,  then  placed  in  position, 
and  its  free  margins  ground  down  even  with  the  root  end. 

Next  prepare  the  band  for  a  pure  gold  floor  by  taking  a  Butler 
corundum  point  and  hollowing  out  the  upper  or  small  end  by 
beveling  from  the  inside  edge  so  as  to  allow  room  for  the  solder. 
Although  only  an  infinitesimal  amount  of  solder  runs  inside,  still 
there  must  be  a  place  for  that  little  to  flow ;  otherwise  the  band 
could  not  go  back  into  place,  on  account  of  the  solder  flowing  in- 
side, and  we  must  have  the  solder  to  flow  inside  in  order  to  make 
a  complete  cone  externally.     Now  take  a  piece  of  pure  gold   (No. 


528 


MECHANICAL   DENTISTRY. 


34  American  gage)  and  cut  just  a  little  larger  than  the  band, 
anneal  it  and  adapt  it  perfectly,  then  place  the  two  in  a  No.  7 
Melotte  soldering  clamp  (Fig.  455),  and  be  sure  they  do  not  move; 
place  borax,  mixed  with  water  to  a  thin  cream,  all  around  the  over- 
lapping edge  of  pure  gold,  place  a  small  piece  of  22-carat  gold 
solder  at  the  junction  of  the  band  and  floor,  and  with  a  broad, 
gentle  flame  solder  the  entire  floor  with  the  one  piece  of  solder  and 
at  the  same  moment.     The  clamp  holds  them  firmly  together,  and 

Fig.  455. 


the  work  can  be  placed  back  on  the  tooth  without  rocking.      (Fig. 

456.) 

Now  make  the  pivots  or  dowels  (of  platinum  and  iridium  wire), 
and  roughen  them  before  placing  in  position.  Drill  holes  corre- 
sponding with  the  root  canals,  place  the  pivots  in  position,  and 
fasten  them  to  the  floor  with  prepared  hard  wax.  Now  remove 
carefully,  and  invest  pivots,  floor,  and  band  in  equal  parts  of  plas- 
ter and  marble-dust,  and,  after  removing  the  wax  with  boiling 
water,  unite  them  with  22-carat  gold.     Now  cut  down  the  over- 


Fig.  456.     Fig.  457.         Fig.  458.         Fig.  459. 


Fig.  460. 


lapping  pure  gold  floor  exactly  even  with  the  band,  also  cut  down 
the  projecting  ends  of  the  pivots.  This  constitutes  the  foundation 
for  a  solid  gold  crown.  Never  make  pivots  for  canals  which  cannot 
be  thoroughly  filled  with  cement.  It  is  better  to  shorten  the  pivot 
somewhat  and  make  it  thicker,  and  depend  for  anchorage  only 
upon  the  lower  part  of  the  canal,  as  shown  in  Fig.  457. 

Now  put  the  foundation  in  its  position  in  the  mouth  (upper  jaw, 
for  example),  and  take  an  impression  of  the  whole  upper  jaw  in 


ARTIFICIAL    CROWNS.  529 

modeling-  compound,  also  take  an  impression  of  the  whole  lower 
jaw.  Remove  the  foundation,  and  place  it  with  great  care  exactly 
in  its  proper  matrix  in  the  impression  just  taken,  then  stay  it  to  the 
modeling  compound  with  wax  in  two  or  three  places ;  be  careful 
not  to  move  it  with  the  wax  knife,  dry  the  pivots  and  band  on  the 
inside,  and  cover  the  pivots  with  a  film  of  wax,  also  run  a  film  of 
wax  around  the  band  on  the  inside,  but  be  sure  to  remove  all  wax 
from  the  edge  of  the  band,  because  we  want  that  to  rest  firmly 
upon  the  plaster.  Now  fill  the  impression  with  plaster  to  make  a 
model. 

After  separating  the  model,  remove  the  crown  foundation  from 
the  model  by  making  a  hole,  usually  on  the  palatal  surface,  with  a 
pocket-knife,  through  the  plaster  to  the  apical  end  of  the  pivot. 
Now  place  the  model  and  foundation  in  hot  water,  and  with  a  little 
pressure  on  the  end  of  the  pivot  the  whole  foundation  is  easily 
removed.  Syringe  out  all  wax  from  the  model  and  foundation;  the 
latter  should  then  be  replaced  upon  the  model. 

Next  make  the  stamp  for  a  grinding  surface;  use  for  this  pure 
gold,  34  American  gage,  and  fill  in  the  cusps  with  22-carat  solder. 
Melotte  makes  a  very  fine  set  of  steel  stamps  that  one  can  generally 
make  use  of,  but  a  zinc  cast  can  be  made  in  a  few  minutes  by  simply 
placing  White's  prepared  molding  sand,  always  ready  for  use,  in  a 
ring  and  gently  imbedding  the  grinding  surface  of  a  suitable  tooth, 
and  in  a  minute  by  the  watch  a  small  quantity  of  zinc  can  be  melted 
and  poured  into  the  impression  in  the  sand.  The  molar  or  bicuspid 
stamp  is  made  in  the  usual  way  by  placing  the  pure  gold,  always 
well  annealed,  on  a  piece  of  lead  and  striking  a  few  light  blows  on 
the  die,  which  gives  a  perfect  grinding  surface,  as  seen  in  Fig.  458. 
This  is  the  reverse  side  of  a  stamp  of  a  superior  left  first  molar. 

Next  trim  off  all  surplus  gold,  leaving  the  grinding  surface  as 
represented  in  the  cut.  The  cusps  are  next  filled  with  22-carat 
solder.  The  reason  22-carat  solder  is  used  is,  when  the  whole 
space  between  the  grinding  surface  and  the  foundation  is  filled  in 
with  20-carat  solder  there  is  no  danger  of  the  22-carat  being  melted 
out  of  the  cusps,  and  consequently  no  danger  of  having  an  air- 
bubble  just  under  the  grinding  surface  which,  of  course,  would 
make  itself  visible  after  a  few  days'  use. 

Having  taken  a  full  impression  of  both  upper  and  lower  jaws, 
an  absolutely  correct  articulation  is  secured.  Now  add  wax  to  the 
34 


530  MECHANICAL   DENTISTRY. 

foundation,  which  can  be  removed  from  the  plaster,  until  an  exact 
articulation  with  the  pure  gold  grinding  surface  is  produced. 
After  having  gotten  this  with  hard  wax  so  that  it  may  be  manipu- 
lated without  disturbing  its  position,  continue  to  build  out  the 
tooth  to  its  anatomically  correct  contour  with  wax,  frequently 
trying  it  into  place.  After  the  foundation  is  removed  from  the 
plaster,  the  plaster  is  cut  away  from  between  the  foundation  and 
the  adjoining  teeth  without  disturbing  the  plaster  upon  which  the 
band  rests.  When  this  plaster  is  removed,  wax  is  added  up  to  the 
very  edge  of  the  band,  so  that  the  entire  anatomical  contour  can 
be  restored  with  gold,  including  even  that  of  the  enamel  chipped 
off  at  the  cervical  margin.  The  wax  tooth  should  always  be  tried 
in  the  mouth,  to  be  sure  that  'everything  pertaining  to  form,  con-* 
tour,  and  position  is  just  right.  This  was  the  object  of  removing 
the  foundation  from  the  plaster  model  at  the  outset,  as  it  is  a  great 
advantage,  and  particularly  so  with  facings,  to  always 
Fig.  461.       just  at  f^-g  t-me  try  tne  j-QQth  in  the  mouth. 

Now  from  a  piece  of  tin-foil  (No.  60)  a  model  is  cut 
so  as  to  fit  the  wax  exactly.  We  cut  the  gold  on  the 
palatal  surface  from  the  height  of  foundation  (see  A, 
Fig.  459),  thereby  enabling  us  to  join  the  free  ends  at 
the  cervicopalatal  surface.  The  large  ends  of  the  gold 
we  turn  out  and  back,  to  stay  it  in  the  investment  of 
plaster  and  marble-dust.  The  gold  can  be  cut  a  little  long,  to  allow 
of  bringing  the  cervical  ends  together.  This  cervical  margin  is  very 
important,  as  shown  in  Fig.  460.  Sometimes  three  pieces  of  gold 
are  used  instead  of  one,  but  if  so  the  pieces  of  gold  should  always 
be  cut  with  projections  (as  seen  in  Fig.  459)  to  retain  the  exact 
shape  of  the  tooth  and  not  pull  it  from  the  instrument  when  sol- 
dered. This  gold  band  must  fit  just  under  the  edge  of  the  grind- 
ing surface  stamp,  and  be  in  perfect  contact  with  it,  so  as  not  to 
allow  the  grinding  surface  to  move.  This  little  thickness  of  pure 
gold  (No.  34  American  gage)  must  be  allowed  for  waxing  up  the 
tooth. 

Now  we  have  the  wax  tooth'  thoroughly  boxed  in,  excepting  the 
palatal  surface.  Before  taking  the  next  step,  be  sure  that  the  pure 
gold  band  for  boxing  is  in  contact  with  the  cervical  margin  of  the 
foundation  band.  At  the  point  of  junction  here  and  at  the  grinding 
surface  place  a  little  wax,  and  then  cut  all  possible  surplus  away, 


ARTIFICIAL    CROWNS. 


531 


leaving-  only  the  very  junction  filled;  also  be  sure  no  wax  gets  on 
the  inside  of  the  cervical  margin  of  the  foundation  band.  Now 
place  the  tooth  in  water  and  invest  it  in  plaster  and  marble-dust, 
covering  the  whole  tooth  except  the  palatal  surface  of  the  crown ; 
the  plaster  must  just  cover  the  narrow  gold  joined  at  the  cervical 
margin.  After  the  plaster  sets,  boil  out  the  wax  and  cut  the  in- 
vestment as  small  as  possible,  leaving  the  plaster  only  about  l/§  of 
an  inch  all  around.  Now  dry  thoroughly,  but  not  in  contact  with 
a  flame ; '  have  something — a  top  of  a  tin  box,  for  instance — be- 
tween the  flame  and  the  tooth.  After  it  is  dry,  place  it  in  the  flame 
of  a  small  Bunsen  burner.  To  hasten  the  heating  up  process,  a 
foot  blowpipe  may  be  used  to  get  it  red-hot  very  quickly,  but 
nevertheless  the  heating  up  is  to  be  done  cautiously,  and  during 
this  time  we  still  have  the  little  Bunsen  flame  under  it.  Now,  by 
applying  the  flame  of  the  Knapp  blowpipe,  the  gold  flows  with  the 
greatest  ease  in  all  parts  and  in  all  directions.  Here  use  20-carat 
solder.  Fill  the  molar  about  half  full  with  gold,  using  borax  as  a 
flux,  before  using  the  Knapp  blowpipe. 

It  should  be  observed  that  we  have  the  solder  almost  to  the 
melting-point,  everything  is  .red-hot,  and  a  hot  flame  beneath  the 
investment,  so  that  when  we  gently  apply  the  blowpipe  flame 
the  gold  simply  drops,  and  while  in  this  molten  condition  add  the 
rest  of  the  solder,  never  allowing  it  to  cool  for  one  moment,  for 
if  it  does  air-bubbles  will  result.  Here  the  gold  boxing  band  at 
the  cervicopalatal  margin  does  its  work  beautifully;  the  gold  flows 
freely  all  around,  with  no  danger  of  solder  running  inside  the 
foundation  from  the  palatal  side.  The  plaster  and  marble-dust 
should  always  be  worked  as  stiff  as  possible,  so  as  to  always  have 
the  gold  in  contact  with  plaster,  which  will  not  be  the  case  if  the 
investment  is  mixed  thin.  The  necessity  of  having  everything  firmly 
held,  so  that  the  gold  solder  will  not  pull  it  in  and  change  the  entire 
shape  of  the  crown,  becomes  evident  when  the  large  amount  of  solder 
used  is  considered.  This  being  a  solid  crown,  we  put  it  in  water  to 
cool,  and  next  in  very  dilute  sulphuric  acid,  and  gently  heat  it  to  re- 
move adhering  borax  and  oxidation.  Now  we  can  shape  the  gold  to 
anatomically  correct  contour  lines  and  bring  the  cervical  margin 
down  to  a  feather  edge,  so  that  when  again  placed  on  the  root  we 
have  an  absolute  junction  without  a  lodging  place  for  acids,  and  the 
whole  tooth  restored  to  a  state  of  perfection.      (See  Fig.  461.) 


MECHANICAL    DENTISTRY. 


In  the  construction  of  a  crown  with  a  porcelain  face,  the  root  is 
shaped  just  as  for  a  solid  crown,  excepting  that  it  is  cut  under  the 
gum  on  the  labial  surface,  and  also  lower  on  the  palatal  surface, 
so  as  to  remove  all  enamel  (Fig.  462).  After  cutting  under  the 
gum  hold  the  gum  back  by  anchoring  premium  gutta-percha  in 
the  root  canal  and  press  it  over  the  labial  surface.  After  the  crown 
has  been  set,  the  gum  comes  down  beautifully  over  the  gold  band 
and  prevents  its  being  visible.  Prepare  and  complete  the  founda- 
tion the  same  as  for  the  solid  crown,  taking  impressions,  bite,  etc., 


Fig.  462. 


Fig.  463. 


Fig.  464. 


as  before,  and  select  the  shade.  Now  prepare  the  facing 
carefully  as  follows :  Grind  the  facing  shorter  than  you 
desire  by  the  thickness  of  No.  34  gold  plate;  grind  off 
both  angles  left  at  the  cervical  portion,  and  also  grind 
the  cutting  edge  on  the  palatal  side  from  pins  to  cutting 
edge,  leaving  a  feather  edge  at  the  cutting  surface ;  like- 
wise grind  the  cervical  portion  from  pins  to  cervical 
margin,  leaving  this  margin  also  a  feather  edge ;  also 
remove  angles  from  pins  to  approximal  margins,  the 
object  being  to  give  a  perfectly  convex  contour  to  the 
palatal  side  of  the  facing. 

After  grinding  off  the  heavy  angles  with  the  lathe, 
use  discs  in  the  engine,  and  be  sure  that  all  angles  are 
removed.  Sometimes  it  is  even  necessary  to  go  be- 
tween the  pins  with  a  disc.  Now  take  Scotch  stone  and  make 
the  surface  perfectly  smooth,  edges  particularly,  or  the  gold 
cannot  be  brought  in  absolute  contact.  Three  different  views 
of  a  facing  so  prepared  are  shown  in  Fig.  463.  The  surface 
where  the  pins  arc  being  the  highest  part,  the  grinding  of  the 
palatal  surface  is  done  so  as  to  fill  in  with  20-carat  solder  and 
give  all  the  strength  that  would  be  obtained  if  we  ground  the 
cutting  edge  off  square,  for  when  the  tooth  is  finished  we  have  a 
slightly  beveled  surface  of  gold  at  the  cutting  edge,  the  facing  hav- 


ARTIFICIAL    CROWNS.  533 

ing  only  a  feather  edge;  but  that  edge  is  well  protected,  so  we  get 
great  strength.  We  secure,  besides,  artistic  beauty  by  having  the 
facing  exactly  the  shape  of  the  natural  tooth  on  the  whole  labial 
surface.  By  this  method  of  shaping  the  facing  we  never  have  a 
tooth  to  crack,  because  there  are  no  angles,  and,  finally,  the  solder 
will  flow  perfectly  around  the  cervicolabial  surface. 

Now  take  this  facing  (being  sure  that  the  palatal  surface  is  clean) 
and  back  it  with  pure  gold,  No.  34,  allowing  the  gold  to  project  a 
little  at  both  cervical  and  cutting  edges.  In  order  to  back  this  facing 
so  that  the  pure  gold  is  in  absolute  contact  with  the  facing, 
anneal  several  times,  each  time  pressing  it  in  contact  with  the  fac- 
ing with  a  broad  instrument  like  a  plastic  spatula  No.  20  (Fig.  464). 
Never  stop  annealing  and  working  to  place  until  the  tooth  can  be 
held  in  contact  with  the  backing  at  the  cutting  edge  and  permits 
no   motion   of  gold  at   the   cervical   margin.     The   same   with   the 

Fig.   465.  Fig.   466.  Fig.   467. 


approximal  surfaces.  Now  hold  the  tooth  and  backing  tightly 
between  the  thumb  and  middle  forefinger,  and  with  the  point  of  a 
pocket-knife'  push  the  gold  into  hard  contact  with  the  pins  all 
around,  using  the  very  point  of  the  knife,  and  there  will  be  no  occa- 
sion to  bend  the  pins ;  besides,  it  makes  a  perfect  gold  surface. 

Place  the  facing  with  its  backing  on  the  foundation,  wax  up  with 
hard  wax,  and  try  it  in  position  in  the  mouth.  If  doubt  exists  as 
to  the  correctness  of  the  position,  stay  it  well  with  hard  wax,  then 
try  again  for  position.  After  obtaining  it,  finish  waxing  up  until 
the  contour  is  anatomically  correct,  leaving  a  little  margin  all  around 
the  backing  so  as  to  be  perfectly  boxed  in.  This  is  done,  just  as  in 
the  case  of  the  molar,  by  making  a  tin-foil  model  (Fig.  465)  and 
bringing  the  gold  into  absolute  contact  with  the  backing,  because 
if  a  small  space  is  left  borax  will  run  through  and  crack  the  tooth. 
Great  care  must  be  exercised  with  regard  to  this  contact. 

This  cuspid  box  may  be  made  in  two  pieces,  joined  at  the  cervico- 


534  MECHANICAL    DENTISTRY. 

labial  surface  the  same  as  seen  at  the  cervicopalatal  and  cutting 
edges.  When  we  bring  the  gold  across  the  cutting  edge,  which 
has  the  gold  projecting  a  little,  not  bent  over  the  edge  but  project- 
ing in  perfect  contact,  make  the  pure  gold  go  just  a  little  lower  than 
the  cutting  edge,  so  as  to  have  a  little  bevel  of  20-carat  gold, 
so  slight  that  it  cannot  be  seen  (Fig.  466).  For  exceedingly  heavy 
use  leave  the  bevel  a  little  thicker,  but  even  that  is  scarcely  notice- 
able. Xow  fill  in  the  junction  of  the  boxing  with  the  backing,  and 
also  of  the  cervical  margin  of  the  foundation  with  wax,  and  invest 
the  same  as  for  a  solid  crown,  allowing  the  plaster  and  marble-dust 
to  come  over  the  cervicopalatal  boxing,  etc. 

To  solder  this  crown,  place  but  a  few  pieces  of  20-carat 
solder  and  borax  in  before  using  the  blowpipe,  because  we 
want  the  first  gold  to  flow  perfectly  at  the  cervicolabial  sur- 
face and  so  avoid  air-bubbles,  after  which  the  course  is  clear. 
After  the  soldering  is  completed,  place  the 
crown  under  a  little  box,  so  that  it  may 
cool  off  slowly  and  no  draft  can  reach 
it.  When  cold,  boil  in  dilute  sulphuric 
acid.  This  gold  will  cut  down  absolutely 
in  contact  with  the  tooth,  and  when  the 
cutting  edge  is  finished  with  a  slight  bevel, 
it  will  be  seen  and  understood  what  great 
strength  has  been  secured,  with,  at  the  same  time,  a  beautiful 
labial  facing  of  porcelain.  When  the  cervical  surface,  in  fact  the 
whole  crown,  is  finished  up  in  the  thorough  and  artistic  manner  of 
which  it  is  capable,  it  becomes  a  piece  of  perfection.  (See  Fig. 
467.) 

A  bicuspid  is  made  exactly  the  same  as  a  cuspid,  with  the  ex- 
ception of  the  stamp.  Make  the  stamp,  and  fill  the  cusps  with 
22-carat  solder,  then  hollow  out  the  buccal  cusp  to  fit  the  cusp  of 
the  facing,  and  place  a  very  narrow  piece  of  pure  gold  at  the  junc- 
tion on  the  buccal  surface,  and  continue  as  in  the  cuspid.  (See 
Fig,  468. )  1  f  the  bicuspid  is  a  short  one,  do  not  be  afraid  of  crack- 
ing die  facing;  grind  and  make  it  exactly  as  directed,  and  it  will 
not  crack.     Notice  the  curve  in  the  bicuspid  cut. 

For  a  bridge  tootb,  take  a  superior  right  cuspid.  Now,  when 
grinding  a  tooth  to  fit  the  gum  we  necessarily  expose  the  small 
porosities  in  the  body  of  the  tootb,  winch  always  have  a  tendency 


ARTIFICIAL    CROWNS.  535 

to  lodge  food,  thus  producing  an  offensive  breath.  To  correct  this 
defect,  shape  up  this  cuspid  exactly  the  same  as  if  we  were  making 
a  crown,  and  back  it  up  the  same  way.  Now  flow  wax  over  the 
whole  surface,  and  regulate  the  thickness  of  the  wax  according  to 
the  required  fullness  of  the  tooth,  boxing  in  with  pure  gold  the 
height  of  the  wax  and  restoring  the  shape  of  the  lost  tooth ;  then 
invest  to  the  top  of  the  boxing,  and  after  the  proper  steps  of  invest- 
ing fill  in  with  gold.  Here  there  are  two  great  points  to  observe. 
First,  this  gold  can  be  finished  absolutely  smooth,  so  that  nothing 
can  collect  in  the  way  of  food,  hence  nothing  but  perfect  cleanliness 
can  exist.  Secondly,  any  amount  of  absorption  of  gum  can  be  coun- 
teracted by  building  out  with  gold  exactly  the  amount  of  absorp- 
tion. This  will  give  the  tooth  a  natural  position,  a  perfectly  smooth 
palatal  surface,  and  restore  the  lip  to  its  normal,  or,  in  case  of  a 
cuspid,  almost  normal,  expression. 

Dr.  Mason's  System. — It  has  long  been  the  desire  of  the  pro- 
fession to  overcome  the  annoyance  caused  by  the  breakage  of  the 
porcelain  facings  in  crown-  and  bridge-work.  Many  efforts  have 
been  made  to  produce  detachable  facings,  but  prior  to  the  intro- 
duction of  the  *Mason  crown  none  has  been  designed  that  could 
be  manufactured  and  sold  to  the  dentist  for  his  immediate  use. 
Through  the  efforts  of  Dr.  W.  L.  Mason,  a  system  of  corresponding 
dovetail  and  groove,  and  a  process  of  manufacturing  whereby  a  por- 
celain facing  is  made  independent  of  its  backing,  has  been  devised. 
Figs.  469,  470,  and  471  represent  the  manner  of  constructing  a 
superior  cuspid  crown.  Fig.  469  shows  the  root,  prepared  in  the 
usual  way  for  the  reception  of  a  collar  crown,  with  the  Mason 
metallic  backing  adjusted  to  same ;  also  the  back  face  of  a  cuspid 
facing,  showing  the  dovetail  attachment,  which  is  baked  in  the 
body  of  the  tooth.  Fig.  470  shows  the  same  tooth  being  adjusted 
to  the  backing,  while  in  Fig.  471  we  have  the  crown  complete,  the 
same  principle  being  carried  out  in  any  other  tooth  and  in  bridge- 
work. 

The  tooth,  with  its  dovetail,  is  fitted  to  the  band  by  grinding  out 
where  necessary.  Then  the  gold  backing  is  waxed  to  the  band, 
and,  after  wax  is  hard,  the  porcelain  is  removed  from  its  backing, 
by  taking  hold  of  extended  portion  of  dovetail,  and  drawn  from 
same.  The  crown  without  the  porcelain,  is  now  ready  to  invest  for 
soldering.     First  the  dovetail  groove  is  filled  up  with  Mason's  invest- 


536 


MECHANICAL    DENTISTRY. 


ment  material,  to  keep  out  the  solder,  which  it  will  do  perfectly, 
then  the  piece  is  invested  as  usual,  letting  the  plaster  come  well 
over  the  cutting  point  of  backing.  It  is  now  ready  for  soldering, 
and  can  be  heated  up,  soldered,  and  cooled  off  as  quickly  as  desired. 
After  removing  from  investment,  the  groove  should  be  thoroughly 
cleansed  and  dried;  also  the  dovetail  in  porcelain.  Now  take 
some  chlora-percha,  quite  thick,  fill  up  groove,  and  press  porcelain 
home.  Saw  off  (never  cut)  the  extended  portion  of  metal  dovetail 
and  finish  as  usual.  Porcelain  can  also  be  cemented  on  with  cement 
or  sulphur.  For  use  as  a  dummy,  articulate  to  position,  remove, 
and  solder  "  stop  "  to  neck  of  backing  to  prevent  porcelain  from 
slipping  upward ;  replace  on  model,  join  parts  with  wax,  then  with- 
draw the  porcelain  and  invest. 

The  advantages  gained  by  this  method  can  only  be  appreciated 


Fig.  469. 


Fig.  470. 


Fig.  471. 


by  practice.  The  first  is  that  we  do  not,  at  any  time,  have  to  place 
the  teeth  under  the  flame  of  the  blowpipe ;  second,  we  are  not 
annoyed  by  the  changing  of  color  which  takes  place  in  soldering; 
third,  a  solid  backing,  without  bubbles;  fourth,  the  invested  piece 
can  be  quickly  heated,  soldered,  and  cooled ;  fifth,  the  small 
amount  of  solder  necessary — just  enough  to  join  parts  together; 
sixth,  saving  the  porcelain  from  being  etched  by  borax;  seventh, 
we  are  able  to  fit  a  bridge  releasing  the  strain  by  cutting  and 
resoldering  and  not  have  the  porcelain  interfered  with ;  eighth, 
the  most  important  of  all,  the  amount  of  time  saved  to  the  busy 
dentist  in  making  repairs,  it  being  accomplished  in  a  few  minutes. 


ARTIFICIAL    CROWNS.  537 

THE    ALL-GOLD    CROWN    OR    CAP. 

In  the  construction  of  the  all-gold  crown,  the  sides  of  the  natural 
crown  and  neck  of  the  tooth  are  brought  down  to,  or  a  little 
smaller  than,  the  size  of  the  root.  This  is  best  accomplished  by 
the  use  of  diamond  discs  and  small  corundum  stones  on  the  dental 
engine.  From  the  occluding  surface,  if  any  of  it  remains,  a  suffi- 
cient amount  should  be  ground  away,  and  the  edges  slightly 
rounded,  to  allow  the  introduction  of  the  gold  cusps.  The  meas- 
urement and  making  of  the  band  is  the  same  as  described  in  con- 
nection with  the  Richmond  collar  crown  (see  p.  503),  excepting 
in  the  width  of  the  ferrule.  This  should  extend  from  the  root, 
below  the  gum-margin,  to  within  a  line  of  the  occlusion  with  the 
antagonizing  teeth.  After  soldering  and  adjusting,  the  band  should 
be  shaped  and  contoured  with  burnishers  and  suitable  pliers,  the 
smooth,  round-nosed,  answers  very  nicely.  The  surface  of  the  band 
to  which  the  cusps  are  to  be  attached  should  then  be  brought  down 
perfectly  smooth  and  flat  with  a  fine  file;  readjusted  carefully  to  the 
root,  to  make  sure  that  it  has  not  been  so  distorted  by  the  different 
manipulations  that  it  will  not  pass  readily  to  place  and  fit  the  root 
perfectly  at  every  point.  Finding  all  correct,  the  next  step  is  mak- 
ing the  cusp. 

A  number  of  methods  have  been  put  forward  for  making  gold 
cusps.  The  two  that  have  proven  most  satisfactory  are  the  use  of 
the  die,  such  as  described  in  connection  with  the  Knapp  system  of 
making  crowns,  and  by  means  of  the  die  plate  as  described  by  Dr. 
E.  T.  Starr,  in  the  Dental  Cosmos,  as  follows: 

In  the  construction  of  metal  cap  crowns  to  cover  natural"  teeth 
or  roots  there  are  many  methods  which  result  in  good  work,  but  in 
most  cases  the  caps  do  not  articulate  as  well  as  they  might,  for  the 
reason  that  means  for  embossing  the  bicuspid  and  molar  cusps  are 
not  at  hand,  or  available  within  the  short  time  at  the  disposal  of 
either  the  patient  or  the  dentist.  With  the  object  of  providing  an 
easy  and  quick  way  of  working  under  such  circumstances,  I  have 
made  a  single  plate,  Fig.  472,  in  which  are  four  groups  of  intaglio 
dies,  representing  with  distinctive  correctness  the  peculiar  cusps  of 
the  upper  and  lower  right  and  left  bicuspids  and  molars.  These 
are  indicated  by  the  Hillischer  notation,  so  that  each  form  may  be 
easily  identified  in  practice. 


538 


MECHANICAL    DENTISTRY. 


The  hubs  A  B,  Fig.  473,  are  of  the  sizes  shown,  and  are  made  of  an 
alloy  composed  of  tin  one  part,  lead  four  parts,  melted  together.    The 

Fig.  472. 


Fig.  473. 


mold  C  should  be  warmed,  the  melted  alloy  poured  in  every  hole, 
and  the  overflow  wiped  off  just  before  the  metal  stiffens.     This  will 


ARTIFICIAL    CROWNS. 


539 


make  the  butts  of  the  hubs  smooth  and  flat.  After  a  minute  or  two 
the  mold  may  be  reversed,  the  hubs  shaken  out,  and  the  casting 
process  continued  until  a  considerable  number  of  hubs  shall  have 
been  cast. 

In  Fig.  474  a  molar  hub  is  shown  in  place  on  a  piece  of  Xo.  32 

Fig.  474. 


gold  plate,  which  lies  over  the  upper  right  first  molar  die.  A  suc- 
cession of  blows  on  the  hub,  with  a  four-pound  smooth-faced  ham- 
mer, will  drive  the  plate  into  the,  die,  and  at  the  same  time  spread 
the  hub  metal  from  the  center  to  its  circumference  in  such  a  man- 


Fig.  475. 


ner  that  the  plate  will  be  perfectly  struck  up  with  the  least  possible 
risk  of  being  cracked.  The  flattened  hub  is  seen  in  Fig.  475,  which 
also  shows  at  D  the  obverse  of  the  struck  up  hub,  and  at  E  the 
cameo  of  the  struck  up  plate,  having  every  cusp  and  depression 
sharply  defined. 


540 


MECHANICAL   DENTISTRY. 


The  counter-die  plate.  Fig.  472,  is  made  of  a  very  hard  cast 
metal,  which  will  admit  of  the  striking  up  of  many  crown-plates  by 
the  means  and  methods  described,  if  the  crown-plates  be  not  too 
thick  and  stiff.  Of  course,  they  should  be  annealed  before  they 
are  placed  over  the  die.  In  careful  hands  the  die-plate  should  give 
clear  cusp  definitions  after  years  of  use. 

The  peculiar  action  of  the  hub  in  forming  first  the  center  of  the 
crown-plate,  and  spreading  from  the  center  outward,  as  the  hub  is 
shortened  under  the  hammer,  until  the  die  is  overspread  by  the  plate 
and  hub,  with  the  result  shown  in  Fig.  475,  is  an  essential  feature 
of  this  process  for  obtaining  easily  and  quickly  the  superior  styles 
of  coronal  cameos  shown.  If  a  cusp  or  fissure  should  chance  to 
crack   in  hubbing,   a   small  piece  of  plate  may  be   struck   over  it, 


Fig.  476. 

or  another  crown-plate  be  struck  over  the  first  and  the  two  soldered' 
together. 

The  depressions  in  the  struck  plate  can  be  partly  or  wholly  filled 
with  scraps  of  plate  or  solder,  and  the  surplus  plate  cut  away  from 
the  cameo. 

The  fact  is  noteworthy  that,  by  means  of  a  Bunsen  burner  on 
blowpipe,  these  swaged  cusps  may  even  be  filled  with  melted  scraps 
cut  from  the  identical  plate  out  of  which  the  cameo  was  struck. 
The  better  way,  however,  is  to  fill,  say,  a  22-carat  cameo  with  20- 
carat  plate  scraps.  The  fitting  and  soldering  of  the  doubled  or  filled 
cameos  to  suitable  collars  is  a  simple  matter,  and  need  not  be 
described. 

It  only  remains  to  arid  the  statement  that,  by  this  counter-die  and 
hub  process,  gold,  platinum,   silver,  or  other  metallic  cap  crowns,, 


ARTIFICIAL    CROWNS. 


541 


having  finely  formed  and  solid  cusps  for  proper  occlusion  and 
resistance  to  wear,  can  be  made  with  little  trouble  and  in  a  very 
short  time. 

After  securing  a  well-defined  occluding  surface  or  cameo  for  the 
case  in  hand,  it  should  be  filled  with  gold  plate  scraps  or  solder  of 
a  lower  carat,  with  a  little  borax.  This  is  all  held  over  a  Bunsen 
burner  until  the  small  pieces  of  gold  come  to  the  fusing-point  and 
settle  down  into  the  depressions  of  the  shell.  More  small  pieces 
should  then  be  added  until  it  is  level  full.  The  surplus  gold  should 
then    be    trimmed    away,    and    a    file 

passed    several    times    over    the    sur-        Fig.  477.  Fig.  479. 

face  of  the  solder  to  bring  it  down 
perfectly  level  and  smooth.  (See  Figs. 
477  and  478.) 

Before  removing  the  band  from  its 
position  in  the  mouth,  a  small  mark 
should  be  made  with  an  excavator  to 
indicate  the  center  of  the  buccal  sur- 
face, which  will  serve  as  a  guide  for 
the  correct  placement  of  the  cusps. 
The  band  should  then  be  contoured 
with  suitable  pliers  (see  Fig.  476),  to 
suit  the  requirements  of  the  case  in 
hand ;  a  smooth  surface  is  then  given 
to  the  end  which  is  to  receive  the 
cusps,  and  it  will  be  found  that  an 
accurate  joint  between  them  can 
readily  be  secured. 

Having  carefully  noted  the  line  of  occlusion  and  marked  the  band 
to  indicate  the  point  where  the  center  of  the  buccal  surface  of  the 
cusps  or  crown-plate  should  be  placed  and  soldered,  the  two — the 
band  and  the  crown-plate — should  be  carefully  brought  together  and 
secured  with  a  few  strands  of  small  binding  wire.  The  joint  should 
now  be  coated  with  borax  dissolved  in  water,  when  it  is  readv  for 
the  final  soldering.  If  solder  has  been  used  in  filling  the  cusps, 
no  additional  solder  will  be  needed  at  this  time,  as  bv  simply  hold- 
ing the  crown  over  the  flame  of  a  small  Bunsen  burner,  as  shown 
in  Fig.  479,  until  the  solder  is  seen'  to  come  to  the  fusing-point, 


54-  MECHANICAL   DENTISTRY. 

then  instantly  withdrawing  it,  the  crown-plate  and  band  will  be 
united  perfectly.  If,  however,  gold  plate  has  been  used  entirely 
in  forming  the  crown-plate,  a  small  piece  of  solder  will  be  needed 
to  unite  them.  The  crown  is  then  ready  for  the  finishing  proc- 
esses, which  consist  in  filing  or  grinding  off  the  projecting  edges 
of  the  crown-plate  flush  with  the  face  of  the  crown,  and  smoothing 
and  beveling  the  free  edge  of  the  band  or  ferrule ;  the  crown 
should  then  be  adjusted  to  the  root  and  the  occlusion  noted.  If, 
as  is  frequently  the  case,  a  little  of  the  gold  needs  to  be  removed 
at  one  or  more  points,  in  order  to  have  a  perfect  occlusion,  it  should 
be  done  with  a  small,  flat-faced  corundum  stone.  The  crown  should 
then  be  removed  and  polished  at  the  lathe. 

Gold  Seamless  Contour  Crowns. — The  manner  of  construct- 
ing what  is  known  upon  the  market  as  the  "  Evans  Gold  Crowns  " 
we  here  present,  through  the  courtesy  of  Dr.  George  Evans,  who 
says  : 

"  The  artistic  requirement  of  all-gold  crown-work  is,  that  it  shall 
reproduce  the  anatomical  contour  of  the  natural  teeth.  This  is 
usually  accomplished  by  melting  solder  on  the  collar  and  then  trim- 
ming it  to  the  form  of  the  crown.  A  preferable  method  is  to  shape 
the  metal  forming  the  sides  of  the  crown  by  swaging.  This  is 
easily  done  in  a  crown  formed  in  sections,  but  a  special  process 
is  required  in  the  construction  of  seamless  crowns." 

A  contour  crown  can  be  made  by  placing  a  seamless  cap  on  a 
sectional  die  or  mandrel  of  the  shape  of  the  tooth,  first  swaging 
the  grinding  surface  on  the  mandrel  and  then  stamping  downward 
on  the  straight  sides  of  the  crown  with  a  cap  fitted  to  the  shank 
part  of  the  mandrel.  But  such  a  process,  like  many  others,  is  too 
complicated  to  be  of  any  use  to  the  dental  practitioner.  The  sec- 
tional mold  method  here  presented  is  simple,  practical,  and  general 
in  its  application. 

To  describe  and  illustrate  the  process,  we  will  take  one  of  the 
most  difficult  crowns  to  construct — a  superior  molar  (Fig.  480). 
A  natural  tooth,  or  one  made  of  plaster,  is  used  as  a  model.  From 
this  a  sectional  mold  is  made,  as  illustrated  in  Figs.  481  and  482, 
in  Babbitt  metal,  zinc,  or  fusible  alloy.  Into  the  mold  a  cap  of 
gold  (Fig,  483)  23  to  24  carats  fine,  30  to  32  gage,  is  adjusted, 
fitting  tightly  the  orifice  of  the  closed   mold.     The  mold   is  placed 


ARTIFICIAL    CROWNS. 


543 


in  a  vise,  the  cap  expanded  to  the  general  form  of  the  mold  by 
hammering-  into  it  a  mass  of  cotton,  and  then  swaged  more  in  de- 
tail to  the  form,  and  with  a  wood  point  or  a  burnisher  revolved  by 
the  dental  engine  burnished  into  every  part  of  the  mold  (Fig.  484). 
To   facilitate  the  process,   the   mold    should   be    frequently   opened 


Fig.    480. 


Fig.    482. 


^ii> 


and  the  gold  annealed.     Fig.  485  represents  the  completed  crown. 
These  results  can  be  secured  by  other  styles  of  molds. 

Another  method  is  to  form  a  fusible  metal  die  of  the  tooth  to  be 
crowned,  and,  after  having  stamped  the  grinding  surface  of  the 
crown,  to  reverse  and  swage  the  sides  close  to  the  die;  the  crown 


Fig.    484. 


Fig.    485. 


w 


Fig.    486. 


is  then  relieved  of  the  core  (die)  by  heating  to  the  melting-point  of 
the  fusible  metal  and  pouring  it  out. 

For  practical  use  a  variety  of  molds  is  required,  made  from 
natural  teeth  of  different  sizes  and  average  forms  to  serve  in  cor- 
responding cases.  The  crowns  can  be  contracted  at  the  neck  more 
than  their  size  and  contour  call  for,  so  that  the  gold  will  act  as  a 
tight-fitting  band,  which  will  expand  to  the  form  of  the  root  as  the 
crown  is  pressed  up  in  the  process  of  adjustment. 


544  MECHANICAL   DENTISTRY. 

Caps  of  metal  can  be  made  in  different  sizes  and  kept  on  hand 
for  use  in  this  and  other  styles  of  crown-work  by  means  of  a 
machine,  which  in  principle  is  such  as  is  used  by  jewelers  for  form- 
ing cap-shaped  pieces  of  gold,  and  in  factories  for  making  copper 
cartridges.  The  gold  plate,  cut  into  circular  pieces,  is  pressed 
through  a  steel  die-plate,  with  punches  gaged  to  the  holes;  at 
each  punch  a  small  portion  of  the  gold  is  turned  over,  thus  pre- 
venting its  lapping  or  creasing.  Repeated  annealing  of  the  metal 
is  very  necessary  in  this  process. 

Methods  of  Contouring  Crowns  Constructed  in  Sections. — 
In  constructing  a  crown  in  sections,  the  collar  can  be  first  formed 
on  a  mandrel,  then  placed  in  a  mold,  and  burnished  to  the  shape 
of  the  sides.  The  process  of  its  adjustment  to  the  neck  of  the  root 
is  then  continued  in  the  usual  manner. 

Another  method  is  to  stamp  or  burnish  up  the  collar  on  a  die 
representing  the  upper  sections  of  a  tooth,  designated  as  the  mid- 
dle and  cervical  third  (Fig.  486).  After  contouring  the  collar,  the 
cap  is  adjusted  and  soldered  on.  With  a  metallic  stamping  plate 
(see  page  538)  these  caps  are  quickly  made. 

The  Selection  and  Adjustment  of  Seamless  Contour  Crowns. 
— A  superior  molar — one  of  the  most  difficult  teeth  to  operate 
on — will  serve  as  a  typical  case  to  illustrate 
this  process.  The  crown  or  root  is  first 
shaped,  and  if  necessary  built  down  with 
amalgam,  straight,  or  tapering  slightly  on 
its  sides  toward  the  occluding  surface. 

The  width  of  the  crown  required  from  the 
anterior  to  the  posterior  sides  of  the  occlud- 
ing surface  is  first  obtained  by  measurement  with  a  piece  of  card- 
board or  thin  copper  plate,  as  shown  at  A,  Fig.  487.  The  measure- 
ment can  be  taken  direct  from  the  mouth,  or  more  conveniently 
from  a  small  plaster  cast  made  from  a  correct  impression  of  the 
prepared  crown  or  root  and  the  two  approximal  teeth.  This  meas- 
urement can  also  be  taken  by  means  of  tweezers  with  a  set-screw 
(Fig.  488).  With  this  measurement  as  a  guide,  the  proper-sized 
occluding  surface  is  readily  found  by  comparison  with  the  dimen- 
sions of  the  various  crowns  as  shown  on  the  printed  chart  of  the 
crowns  (( ',  Figs.  489  and  490). 

The  size  of  the  neck  can  be  calculated  by  the  eye,  or  by  taking 


ARTIFICIAL    CROWNS. 


545 


the  dimensions  with  a  piece  of  fine  wire  (Fig.  493),  pressing  the 
wire  on  the  surface  of  a  piece  of  sheet-wax,  and  then  comparing 
with  the  impression  the  necks  of  the  gold  crowns. 

In  making  a  selection,  it  should  be  borne  in  mind  that  the  cervix 
of  the  gold  crown  should  preferably  be  smaller  than  larger,  as  it 

Fig.  488. 


Tweezers  with  set-screw  to  use  as   calipers. 


can  always  be  easily  expanded,  while  its  contraction  is  difficult. 
It  is  not  essential  that  the  curve  of  the  collar  shall  correspond  with 
that  of  the  tooth,  as  the  gold  will  readily  take  the  proper  shape  as 
the  crown  is  adjusted. 

Method    of    Adjusting    the    Crown. — 1.  Anneal    the    crown    se- 


Fig.  489. 


lected,  and  slip  it  over  the  end  of  the  natural  crown  or  root  and 
gently  press  or  work  it  upward — the  gold  of  the  collar  will  expand 
to  the  form  of  the  root  in  the  operation — until  the  edge  meets  the 
margin  of  the  gum  (A,  Fig.  491). 

2.  Mark  a  line  (B)  on  the  gold  parallel  with  the  margin  of  the  gum. 

35 


546 


MECHANICAL   DENTISTRY. 


3.  Remove  and  trim  to  this  line  (A,  Fig.  494).  If  necessary- 
repeat  the  marking  and  trimming  until  the  edge  meets  the  gum 
evenly. 

4.  Bevel  the  edge  of  the  gold,  readjust  the  crown,  and  press  it 
up  until  the  edge   of  the   collar  passes   under  the   margin   of   the 


Fig.  493. 


Fig.  494. 


gum,  and,  if  the  occlusion  is  correct,  burnish  the  gold  to  the  cer- 
vix. 

To  Expand  the  Collar  and  Crown. — If  the  collar  of  the  crown 
needs  enlargement,  it  is  easily  and  most  properly  accomplished  with 
crown  expanders  shown  in  Fig.  495,  the  points  of  which  should  be 
introduced  at  first  just  within  the  edge  of  the  neck,  and  the  gold 

Fig.  495. 


spread  sufficiently  to  allow  it  to  fit  over  the  end  of  the  natural  crown 
or  root,  the  process  of  expansion  being  gradually  continued  as  the 
crown  is  brought  into  position.  By  proceeding  in  this  manner  too 
great  expansion  is  avoided. 

If  the  entire  crown  needs  enlargement,  it  is  best  done  by  soften- 
ing a  mass  of  gutta-percha  of  about  the  same  size  as  the  crown 


ARTIFICIAL    CROWNS. 


547 


Fig.  496. 


upon  the  closed  ends  of  a  pair  of  expanding  or  clamp  forceps, 
which  are  heated  for  the  purpose.  The  forceps  points  with  the 
gutta-percha  are  then  introduced  inside  the  collar  of  the  crown, 
which  should  be  moistened  to  prevent  adhesion.  The  gutta-percha 
is  next  withdrawn,  hardened  in  cold  water,  and  cut  through  the 
center  between  the  points  of  the  forceps.  This  makes  practically 
an  expanding  sectional  mandrel  with  which  the  crown 
can  be  enlarged  according  to  the  position  in  which  the 
forceps  were  introduced  (Fig.  496). 

To  expand  the  crown  without  enlarging  the  neck, 
trim  off  the  gutta-percha  on  the  forceps  at  the  neck. 

The  naked  points  of  an  ordinary  lamp  forceps  can 
sometimes  be  used  to  advantage  in  expanding  a  portion 
of  the  coronal  section  of  the  crown. 

To  Alter  a  Side. — The  contour  of  one  or  both  sides  can  be 
depressed  and  the  crown  thus  narrowed  by  introducing  the 
points  of  a  crown  expander  or  some  tool  that  will  fit  loosely  inside 
the  crown,  then  steadying  the  crown  with  the  fingers,  as  shown  in 
Fig.  393,  and  tapping  the  sides  to  be  reduced  with  the  flat  end  of  a 
riveting:  hammer.     This  is  necessarv  when  the  contour  or  the  side  of 


Fig.  497. 


a  crown  presses  on  an  adjoining  tooth,  and  the  crown  is  thus  pre- 
vented from  coming  in  proper  position. 

To  Alter  the  Shape  of  a  Portion  of  the  Collar  or  Side  of  a 
Crown. — Slip  the  crown  over  the  point  of  an  anvil,  the  end  of  a 
pair  of  expanders,  or  a  small  round-handled  instrument  held  in  a 
vise;  then  tap  the  part  to  be  altered  with  the  flat  end  of  a  riveting 
hammer  to  the  form  desired. 

To  Alter  the  Occluding  Surface. — Before  the  crown  is  pressed 


548 


MECHANICAL    DENTISTRY, 


up  to  its  apparently  proper  position,  the  occlusion  should  be  ex- 
amined, and  calculations  carefully  made  to  obviate  any  defects  of 
articulation,  which  can  be  readily  corrected  at  this  stage  by  proper 
manipulation  of  the  crown.  Any  necessary  change  in  the  form  of 
the  occluding  surface  can  be  made  with  the  crown  in  position  on 
the  tooth,  by  means  of  an  instrument  tapped  by  the  mallet;  by 
removing  the  crown,  placing  it  over  the  closed  points  of  an  ex- 
pander, and  tapping  and  burnishing  the  part ;  or  by  holding  the 
crown  between  the  thumb  and  forefinger  with  the  edge  of  the  collar 
resting  on  the  side  of  the  next  finger,  which  when  necessary  can 
be  protected  with  a  napkin,  and  then  tapping  the  gold  with  the  point 
of  a  riveting  hammer  (Fig.  498). 

The  occluding  of  the  antagonizing  teeth  on  the  crown  by  the 
patient  will  assist  and  complete  the  process  of  articulation. 


Fig.  498. 


Fig.  499. 


To  Contract  the  Neck. — Slightly  bend  in  the  edge  of  the  gold 
at  the  neck  with  narrow-beaked  pliers,  and,  holding  the  crown  evenly 
and  firmly  between  the  fingers,  as  shown  in  Fig.  499,  burnish  the 
sides  of  the  neck  section  inward  around  the  entire  circumference  of 
the  crown. 

To  Considerably  Contract  a  Crown. — Slit  the  gold  longitudin- 
ally at  the  palatal  side,  nearly  its  full  length  to  the  grinding  sur- 
face, bevel  off  the  edge  to  lap  under,  contract  the  crown,  readjust 
to  the  tooth,  remove,  place  the  smallest  quantity  of  dampened  fluxed 
solder  filings  in  the  seam  on  the  inside  of  the  crown  only,  and  solder 
by  holding  in  an  alcohol  flame.  Then  proceed  with  the  further 
adjustment  of  the  crown. 

The  outside  line  of  the  seam  can  be  stoned  off  and  polished  after 


ARTIFICIAL    CROWNS. 


549 


the  crown  has  been  fitted,  and  additionally  soldered  to  strengthen 
the  sides  or  grinding  surface. 

Strengthening  Seamless  Gold  Contour  Crowns. — Additional 
strength  and  stiffness  can  be  given  to  seamless  gold  crowns,  when 
desired,  in  several  ways.  The  liability  of  melting  the  gold  which 
forms  the  sides  of  the  crown  in  the  operation  has,  with  some,  been 
the  principal  objection  to  their  use.     This,  however,  can  be  avoided. 

When  the  crown  has  been  properly  adjusted,  dampen  the  inner 
surface  with  a  piece  of  wet  cotton  on  the  point  of  an  instrument; 
place  in  the  interior  a  quantity  of  fluxed  solder  filings  (solder  filings 
mixed  with  Parr's  flux  or  pulverized  vitrified  borax)  ;  place  the 
finger  over  the  open  end  of  the  crown,  invert,  and  shake  well.  A 
portion  of  the  solder  filings  will  adhere  evenly  all  over  the  wet  sur- 
face. The  surplus  is  allowed  to  drop  out  by  removing  the  finger. 
Then  gradually  and  uniformly  heat  the  crown  by  holding  it  with 
tweezers  in  an  alcohol  flame  (not  gas)  until  the  solder  fuses,  when  it 
will  flow  evenly  over  the  surface  of  the  gold  without  materially 
altering  the  general  form.  The  crown  should  be  held  in  such  a 
position  that  a  full  view  of  the  interior  is  presented  and  the  melting 
of  the  solder  rendered  visible,  which  will  occur  at  a  red  heat. 

An  extra  quantity  of  the  solder  filings  can  be  placed  in  the  inte- 
rior of  the  cusps  with  a  spoon-shaped  excavator  to  additionally  fill 
or  strengthen  them  if  found  necessary. 

When  a  Bunsen  gas  flame  is  used  instead  of  an  alcohol  flame,  the 
grinding  surface  and  sides  of  the  crown  should  be  first  coated'  with 
whiting.  This  is  easily  done  by  dipping  the  crown  into  a  cream- 
like mixture  of  whiting  just  before  inserting  it  in  the  flame.  The 
moisture  in  the  whiting  should  be  first  slowly  evaporated  by  heat- 
ing up  gradually.  Great  care  must  be  exercised  in  the  use  of  a 
gas  flame  to  avoid  melting  the  crown.  The  crown  should  be 
watched,  and  instantly  removed  as  soon  as  the  solder  fuses  and 
flows. 

If  too  much  solder  has  been  applied  at  any  point,  it  can  be 
trimmed  and  smoothed  with  corundum  melted  on  to  an  old  engine 
bur  point.  Always  boil  the  crown  in  acid  to  remove  the  flux.  The 
removal  of  flux  from  the  inner  surface  of  the  crown  is  absolutely 
necessary  if  you  intend  to  use  it  in  bridge-work,  as  solder  will  have 
to  be  melted  on  the  outside. 

To  Repair  a   Gold  Crown. — When  a  hole  is  cut  or  melted  in 


55Q 


MECHANICAL    DENTISTRY. 


Fig.  500. 


any  kind  of  a  gold  crown,  place  a  piece  of  soft  wax  in  the  aperture 
on  the  outside  of  the  crown,  adapt  on  the  inside  close  against  the 
gold  a  piece  of  platinum  foil,  somewhat  larger  than  the  aperture,  so 
that  it  will  adhere  to  the  wax.  Fill  the  interior  of  the  crown  with 
investing  material,  and  flow  a  little  solder  over  the  surface  of  the 
platinum  and  gold  on  the  outside  of  the  crown. 

Gold  seamless  crowns  can  also  be  strengthened 
or  filled  with  solder,  or  even  18-  or  20-carat  gold 
plate,  by  investing  the  outside  surface  in  plaster 
and  marble-dust  (Fig.  500),  and  then  with  a  small 
flame  of  the  carbo-oxyhydrogen  blowpipe,  not  over 
Yz  of  an  inch  in  length,  introduced  inside  of  the 
crown,  melt  and  flow  the  solder  or  gold  plate  over 
any  portion  or  even  all  of  the  surface  of  the  gold. 
The  crown,  if  formed  of  gold  with  a  thin  lining  of 
platinum,  can  be  soldered  by  either  method  with 
little  danger  of  being  melted. 
Supporting  the  Crown. — In  crowning  teeth  with  living  pulps 
there  is  sufficient  of  the  natural  crown  present  to  afford  a  secure 
foundation  and  attachment  for  the  artificial  crown,  as  is  also  the 
case  with  many  teeth  that  are  pulpless ;  but  in  badly  broken-down 
crowns,  or  where  only  the  root  is  present,  a  metallic  pin  or  post 
should  be  inserted  in  the  root,  and  the  part  built  down  with  amal- 
gam to  a  form  which  will  afford  secure  support  and 
attachment  to  the  artificial  crown  and  facilitate  its  ad- 
justment. 

In  many  cases  the  required  support  for  the  crown  can 
be  secured  by  means  of  a  screw  (Fig.  501).  A  How 
screw  or  a  post  of  silver  wire  is  inserted  in  the  root 
canal  A.  Amalgam  is  then  packed  in  the  lower 
section  of  the  artificial  crown  C  to  the  line  B,  and 
the  screw  is  pressed  into  the  amalgam.  Amalgam 
which  has  been  put  in  a  piece  of  chamois  and  the  mer- 
cury pressed  out  with  a  pair  of  pliers  until  it  is  in  the  condition 
termed  "  dry  "  will  adhere  to  the  gold  without  affecting  it.  The 
amalgam  is  first  placed  in  the  crown  slightly  in  excess  of  the 
amount  required,  and  the  crown  adjusted,  removed,  and  the 
surplus  scraped  out.  This  process  is  continued  until  the  screw  or 
the  crown  section  of  the  natural  tooth  forms  an  indentation  in  the 


Fig.  'soi. 


ARTIFICIAL    CROWNS. 


551 


amalgam,  which  it  will  fit  when  the  crown  is  cemented  on.  The 
vent  for  the  escape  of  air  and  surplus  cement — which  should  always 
be  put  in  perfect-fitting  crowns  and  afterward  filled  with  gold  or 
amalgam — should  be  in  the  line  of  the  indentation  in  the  amalgam, 
with  which  it  must  connect  (D). 

These  crowns  can  be  inserted  in  an  easy  and  inexpensive  manner 
by  filling  in  the  lower  section  of  the  crown  with  amalgam  instead 
of  gold,  and  allowing  the  head  of  the  screw  or  the  natural  crown  to 
indent  the  amalgam  as  above  described,  and  then  cementing  on  the 
crown  with  oxyphosphate  in  the  usual  manner. 

In  a  case  so  inserted,  with  no  antagonizing  teeth,  the  result  is  the 
same  as  though  the  inside  of  the  occluding  surface  of  the  crown  was 
filled  with  gold ;  but  if  antagonizing  teeth  are  present,  the  gold  of  the 
crown  is  apt  to  wear  through  in  places  and  expose  the  amalgam. 

To  Securely  Attach  a  Crown. — If  the  tooth  is  short,  and  the 
occlusion  of  a  character  requiring  the  reduction  of  the  collar  to 
such  a  degree  as  to  suggest  insecurity  when  the  crown  is  cemented, 
a  barbed  or  headed  pin,  which  will  anchor  in  the  natural  crown  or 
root,  should  be  soldered  in  the  center  of  the  gold  crown.  This  is 
done  by  passing  the  pin  through  a  hole  drilled  in  the  occluding 
surface  of  the  crown,  which  is  then  adjusted  in  the  mouth,  removed, 
invested,  and  the  pin  soldered  from  the  outside.  If  the  pin  is 
tapered  and  fitted  tightly  to  the  hole,  the  soldering  can  be  accom- 
plished without  investing,  by  holding  the  crown  and  pin  with  sol- 
der in  position  in  an  alcohol  flame. 

To  Alter  a  Gold  Crown  to  the  Exact  Form  of  any  Corres- 
ponding Natural  One. — In  a  case  having  nearly  all  the  natural 
teeth  present,  in  which  the  occluding  surface  and  sides  differ  in 
shape  from  the  form  of  the  gold  crown,  to  such  an  extent  as  to  in- 
terfere with  its  adjustment,  a  die  of  the  natural  crown  should  be 
made  of  fusible  metal  (Melotte's  fusible  alloy),  and  with  it  the  in- 
terior of  the  gold  crown  should  be  altered  in  shape  sufficiently  to 
receive  the  natural  crown,  by  resting  the  occluding  surface  of  the 
gold  crown  on  a  folded  napkin  and  gently  tapping  the  die  into  it. 

The  advantages  of  seamless  contour  crowns  are,  that  they  represent 
perfectly  the  tooth  in  its  anatomical  contour,  present  a  uniform  sur- 
face of  pure  gold,  which  preserves  its  color  without  tarnishing,  and  are 
quickly  and  easily  adjusted.  Their  defects  are  inability  to  meet  the  re- 
quirements of  abnormally-shaped  roots  and  anomalous  articulations. 


CHAPTER    XXXI. 
BRIDGE  DENTURES. 

To  the  skilled  dentist,  well  versed  in  crown-work,  bridge-work 
does  not  present  any  great  difficulty,  inasmuch  as  crowns  are  the 
beginning  and  the  end;  it  is  practically  continuous  crown-work, 
though  many  of  the  crowns — those  rilling  or  bridging  the  space 
where  the  roots  have  been  removed — have  neither  collars  nor  posts. 
In  constructing  these  teeth,  the  matter  of  cleanliness  should  espe- 
cially be  considered ;  where  it  is  admissible  to  allow  them  to  come 
in  contact  with  the  gum  tissue  (as  in  the  anterior  part  of  the 
mouth),  only  the  cervical  porcelain  tips  should  touch.  The  metallic 
backing  and  solder  should  recede,  leaving  self-cleansing  spaces. 

Some  diversity  of  opinion  exists,  however,  as  to  the  advisability 
of  permanently  fixing  such  appliances  in  the  mouth.  Prominent 
among  the  objections  urged  is,  that,  in  the  event  of  accident  to  the 
porcelain  facing  of  the  crown,  there  is  no  sufficient  remedy  without 
detaching  the  entire  piece,  of  which  the  teeth  are  a  part.  It  is 
further  objected  that  a  stationary  fixture  of  this  kind  in  the  mouth 
must  become  not  only  offensive  from  the  accumulation  and  reten- 
tion of  oral  debris  incapable  of  adequate  dislodgment,  but  a  source 
of  injury  to  the  remaining  natural  teeth,  which  necessarily  follows 
the  prolonged  retention  of  alimentary  substances  exposed  to  con- 
ditions so  favorable  to  fermentation  and  putrefactive  decomposi- 
tion. 

On  the  other  hand,  the  writer  entirely  agrees  with  many  compe- 
tent, intelligent,  and  conscientious  operators,  who,  from  observa- 
tion and  experience,  are  qualified  to  form  a  just  estimate  of  the 
merits  or  demerits  of  bridge  dentures,  and  who  bear  testimony  in 
unqualified  commendation  of  its  superior  excellence  when  skilfully 
performed  under  conditions  that  justify  the  operation,  and  claim  for 
it  as  complete  exemption  from  the  alleged  objections  as  is  obtained 
in  the  use  of  any  other  mode  of  replacement  in  similar  cases. 

In    fact,   herein,    we   think,    lies   the   secret   of   either   success   or 

552 


BRIDGE   DENTURES.  553 

failure  in  connection  with  bridge  dentures,  for  it  is  in  the  construc- 
tion of  this  class  of  dentures,  more  than  any  other,  that  unusual 
mechanical  skill  is  required,  and  professional  judgment  needed  for 
determining  where  they  are  admissible. 

Limitations. — For  the  support  of  bridge  dentures,  strong, 
healthy  roots  are  required,  and  the  width  of  the  space  to  be  spanned 
must  be  governed  by  the  size  and  strength  of  these  points  of  anchor- 
age. Whether  a  full  upper  or  lower  denture  can  be  supported  by 
four  points  of  attachment  depends  upon  the  relative  smallness  of 
the  jaw,  the  size  and  strength  of  the  roots  and  teeth,  and  the  occlu- 
sion, the  operator  always  being  governed  by  the  exact  condition  of 
individual  cases. 

Before  entering  upon  a  more  general  consideration  of  the  subject, 
it  may  be  helpful  to  give  a  few  reflections  or  suggestions  in  the  way 
of  typical  cases,  as  follows : 

One  strong  central  root  will  support  two  teeth,  that  is,  the  crown 
and  either  the  adjoining  central  or  lateral.  Two  central  roots  will 
support  the  four  incisors.  Two  strong  cuspid  roots  alone,  or  with 
the  aid  of  a  central  root,  will  support  the  six  anterior  teeth.  A 
cuspid  root  and  a  strong,  healthy  second  or  third  molar  on  the 
same  side  will  support  the  intervening  teeth.  One  molar  or 
bicuspid  on  one  side,  and  a  bicuspid  or  molar  on  the  other,  with 
one  or  two  central  roots,  will  support  a  bridge  between  them.  One 
right  and  one  left  molar,  with  the  assistance  of  the  two  cuspid 
roots,  when  the  conditions  are  favorable,  as  spoken  of  above,  will 
support  a  bridge  comprising  the  entire  arch. 

It  should  be  remembered  that  the  preparation  of  the  teeth  and 
roots  for  the  support  of  a  bridge  is  the  same  as  in  ordinary  crown- 
work,  except  that  the  trimming  of  the  sides  and  the  drilling  of  the 
root  canals  should  be,  as  far  as  possible,  in  parallel  lines,,  so  that  in 
the  adjustment  of  the  finished  piece  the  crowns  will  move  readily 
to  their  places. 

STATIONARY    BRIDGE    DENTURES. 

Among  the  simpler  forms  of  substitution  which  may  be  properly 
classed  under  the  head  of  "  bridge-work,'"  is  the  one  in  which  a 
single  artificial  crown  derives  support  from  attachments  made  to 
one  or  more  of  the  adjoining  natural  teeth,  originally  by  a  process 
of  cavity  filling.     The  original  conception  and  practical  application 


554  MECHANICAL   DENTISTRY. 

of  such  a  method  of  supplying'  an  edentulous  space  is  attributed 
to  Dr.  B.  J.  Bing,  of  Paris,  France,  whose  method  of  operating  has 
since  been  greatly  modified. 

Dr.  Webb's  Method. — One  of  the  earlier  experimenters  in  this 
mode  of  replacement  was  the  late  Dr.  Marshall  H.  Webb,  who 
thus  describes  his  method  of  operating  in  these  cases : 

"  The  insertion  of  a  crown  without  plate  or  clasps,  where  no 
root  remains,  is  a  difficult  operation,  but  when  well  performed,  and 
the  crown  attached  to  teeth  that  are  firm  in  their  sockets,  it  is  both 
satisfactory  and  permanent. 

"  The  first  such  operation  performed  by  the  writer  was  com- 
pleted February  12,  1873,  and  the  crown  now  remains  as  firm  as 
when  inserted.  The  operation  was  performed  in  the  following 
manner :  After  suitably  forming  the  cavities  in  the  proximate  wall 
of  each  tooth  next  the  space  left  by  the  loss  of  the  one  that  had 
been  extracted  (unnecessarily)  some  years  before,  an  impression  of 
the  parts  was  taken,  and  a  plain  porcelain  crown  was  selected, 
fitted  to  place,  and  backed  with  gold  plate  (18  carat).  A  por- 
tion of  the  backing  extended  about  i1/*  lines  from  each  side  of 
the  crown  for  insertion  in  the  cavities  prepared  in  the  adjoining 
teeth,  and  to  these  parts  a  gold  wire  was  soldered  to  fit  into  the 
pulp  chamber  of  the  central  and  lateral  incisors.  A  small  gold 
plate  was  then  formed  to  fit  upon  the  gum,  covering  as  much  space 
as  was  taken  up  by  the  neck  of  the  natural  tooth.  The  backing 
was  riveted  to  the  pins  in  the  porcelain,  and  this  placed  in  position, 
and  while  the  whole  rested  on  the  small  plate  upon  the  gum,  the 
backing  and  plate  were  so  secured  by  wax  that  they  could  be  removed 
intact,  and,  after  being  placed  in  a  matrix,  soldered.  Each  extended 
side  of  the  backing  and  the  surface  of  the  wire  was  barbed  with  an 
engraver's  bossing  tool,  so  that  the  gold-foil  would  the  better  secure 
the  crown  when  filled  into  every  part. 

"  The  porcelain,  with  the  gold  attachments,  being  ready  for  in- 
sertion, a  piece  of  light,  medium  rubber  dam  was  put  in  place  on 
two  teeth  each  side  of  the  space  to  be  filled,  and  over  the  gum 
upon  which  the  crown  was  to  rest.  (The  rubber  takes  up  but  lit- 
tle space,  and  this  is  more  than  compensated  for,  when  the  liga- 
ture— waxed  floss-silk — is  pressed  to  or  near  the  neck  of  each 
adjoining  tooth.)  Oxychlorid  of  zinc  was  then  placed  in  the  pulp 
chamber  of  the  central  incisors  and  the  crown  at  once  pressed  to 


BRIDGE    DEXTURES. 


555 


place.  When  the  cement  had  hardened  sufficiently  to  safely  admit 
of  further  progress  in  the  work,  a  portion  of  it  was  cut  away  from 
around  the  wire  so  as  to  make  proper  anchorage  for  the  gold. 
Small  pieces  of  light  cohesive  gold-foil  were  then  impacted  around 
part  of  the  wire  and  that  portion  of  the  plate  extending  into  the 
cavities,  and  the  crown  was  thus  secured.  The  porcelain  and  gold 
attachments  as  prepared  for  insertion,  and  the  crown  in  position, 
are  illustrated  in  Fig.  502. 

"  The  cavity  in  the  central  incisor  was  extended  to  the  cutting 
edge  of  the  tooth,  that  access  might  be  had  to  the  wire  and  both 
sides  of  the  plate;  foil  could  not  otherwise  have  been  put  in  place, 
unless  a  portion  of  the  labial  margin  of  enamel  were  cut  away,  and 
this  would  have  been  objectionable  because  of  the  exposure  of  gold. 

Fig.  502. 


A  small  part  of  the  labial  instead  of  the  cutting  edge  of  the  enamel 
of  the  lateral  was  removed,  for  the  reason  that  there  is  not  such  a 
body  of  tissue  as  to  safely  allow  it  to  be  cut  away  to  the  same 
extent  as  in  a  central  incisor.  The  margin  of  enamel  was  so  formed, 
and  the  foil  so  inserted  and  finished,  however,  that,  though  the  gold 
can  be  seen,  it  is  not  conspicuous. 

"  While  the  operation  just  described  has  thus  far  proved  success- 
ful, yet  there  is  a  possibility  of  the  porcelain  being  broken  from  the 
platinum  pins  which  hold  it  to  the  gold  plate.  To  avoid  such  an 
accident,  a  groove  should  be  cut  on  each  side,  and  along  the  cutting 
edge  of  the  porcelain  (Fig.  503,  b),  that  gold-foil  may  be  impacted 
into  it,  after  a  heavy  backing  of  gold  plate  and  the  wire  have  been 
fixed  in  place  and  soldered.     When  the  groove  has  been  cut  in  the 


556 


MECHANICAL   DENTISTRY. 


porcelain  with  a  fine-edged  corundum  disc,  one  with  an  edge  of  the 
diameter  of  the  gold  wire  selected  for  the  case  should  be  used  to 
make  a  groove  across  the  porcelain  between  the  pins  (Fig.  503,  a), 
into  which  the  wire  to  connect  the  artificial  crown  with  the  natural 
teeth  is  to  be  placed  (Fig.  503,  b),  either  beneath  the  plate,  or  so 
that  the  edges  of  the  latter  may  be  joined  to  it,  as  the  necessities 
of  the  case  may  require. 

"  A  starting-point  should  be  made  either  between  the  gold 
backing  and  porcelain,  or  between  this  and  the  wire,  and  the  latter 
firmly  fixed  in  a  hand-vise  while  the  gold-foil  is  being  impacted 
with  the  electromagnetic  mallet.  When  the  gold  is  properly  and 
solidly  placed  in  the  groove  and  over  the  backing  and  wire,  it  not 
only  aids  in  securing  the  porcelain,  but  the  contour  of  the  crown 


Fig.  503. 


Fig.  504. 


can  be  nicely  filled  out,  and  the  operation  made  durable  and  beau- 
tiful  (Fig.  504). 

"  The  surface  of  the  gold  placed  along  the  base  of  the  crown  to 
the  edge  of  the  porcelain,  and  which  is  to  rest  against  the  gum, 
together  with  the  palatal  portion,  ought  to  be  properly  formed  and 
finished  before  the  crown  is  put  in  place,  and  this  should  be  done 
in  the  manner  before  described.  There  should  be  a  little  space 
between  the  wire  and  cervical  wall  in  each  tooth  to  which  the 
crown  is  to  be  attached,  and  narrow  pieces  of  light  gold-foil  care- 
fully placed  in  this  part,  between  the  wire  and  enamel,  with  small 
curved  instruments  and  the  aid  of  the  mallet;  the  surface  of  the 
gold  at  this  part  at  least  should  be  smoothly  finished  with  very 
narrow  (yV  of  an  inch)  strips  of  fine  emery  cloth  before  the  rubber 
dam  is  removed. 

"  One  of  the  most  satisfactory  operations  the  writer  ever  per- 
formed was  the  insertion  of  a  crown  where  a  cuspid  root  had  been 


BRIDGE    DENTURES. 


557 


extracted  (unnecessarily),  and  the  lady  subjected  to  the  wearing  of  a 
gold  plate  for  some  time.  This  crown  was  prepared  and  the  con- 
tour filled  out  with  foil  as  described  and  as  illustrated  in  Fig.  504, 
but  gold  wire.  No.  13,  was  attached  to  and  built  in  with  the  porce- 
lain, placed  into  the  pulp  chamber  of  the  adjoining  lateral  incisor 
(which  had  been  filled),  and  this  same  wire  extended  from  the 
anterior  to  near  the  posterior  proximate  surface  of  the  first  bicuspid 
tooth,  the  pulp  of  which  remained  in  normal  condition.  The 
crown  was  placed  in  position  with  oxychlorid  of  zinc,  and  cohesive 
gold-foil  was  then  impacted  with  the  electromagnetic  mallet 
around  a  portion  of  the  wire  in  the  root  and  info  the  cavity  in  the 
crown  of  the  incisor,  also  into  the  cavity  in  each  proximate  wall  of 
the  bicuspid  tooth,  as  well  as  around  and  over  the  wire,  joining  the 
two  fillings  through  the  enlarged  fissure. 

"  An  extensive  operation  of  attaching  a  crown  to  adjoining  teeth 
was  performed  by  the  writer  before  the  Pennsylvania  State  Dental 
Society,  in  July,  1879.  ^n  this  case  disintegration  had  taken  place 
in  many  of  the  teeth,  and  cavities  of  decay  had  been  prepared  and 
filled  from  time  to  time.  The  teeth  were  abraded  and  the  dentine 
was  exposed  along  the  entire  cutting  edge  of  each  tooth  that  oc- 
cluded with  another.  The  right  upper  lateral  incisor  had  been 
lost  twelve  years  before.  The  crown  of  the  left  cuspid  tooth  was 
missing,  and  but  a  small  portion  of  the  enamel  and  dentine  of  the 
first  bicuspid  upon  either  side  remained.  These  last  were,  of 
course,  pulpless,  as  also  were  the  right  cuspid  and  central  and  left 
lateral  incisor  teeth,  and  the  pulp  chamber  of  each  of  these  had 
been  filled.  All  the  operations  were  performed  previous  to  the 
insertion  of  the  crown  in  the  space  left  by  the  loss  of  the  lateral 
incisor,  and,  as  this  crown  and  each  cavity  and  pulp  chamber  was 
prepared  for  the  gold,  all  appeared  as  here  illustrated  (Fig.  505).* 

"Gold  wire  (No.  13),  with  a  sharp  thread  cut  upon  it,  was 
screwed  into  the  dentine,  and,  at  the  same  time,  all  the  interstices 
between  the  tissue  and  the  gold  were  filled  with  oxychlorid  of  zinc. 
When  crystallization  had  taken  place,  some  of  the  cement  and  den- 
tine was  removed  from  around  the  wire  with  a  small  bur,  and  a 
groove  was  cut  in  the  dentine  near  the  margin  of  the  root  so  as  to 


*  The    cut    (Fig.    505)    illustrates    the    case    well,    though    there    are    parts    and 
grooves  in  which  to  anchor  the  gold  that  are  not  distinctly  shown. — M.  H.  W. 


558 


MECHANICAL   DENTISTRY, 


secure  proper  and  sufficient  anchorage  for  gold ;  cohesive  foil  (prin- 
cipally Xo.  30)  was  impacted  into  these  parts,  and  the  entire  con- 
tour of  the  crown  was  restored  with  the  electromagnetic  mallet. 
This  crown  was  not  faced  with  porcelain,  because  the  teeth  of  the 
gentleman  for  whom  these  operations  were  performed  are  but 
slightly  exposed  to  view ;  and  then,  too,  the  gold  had  to  be  placed 
over  the  enamel  to  support  and  protect  it  along  the  cutting  edges 
of  all  the  incisor,  the  cuspid,  and  bicuspid  teeth.  A  gold  screw 
was  placed  in  the  pulp  chamber  and  extended  into  the  crown  of 
each  bicuspid  tooth  (Fig.  505).  The  apical  foramen  of  each  pulp- 
less  tooth   was  closed,   and  the  whole  of  each   pulp   chamber  into- 

Fig.  505. 


which  a  wire  was  not  placed  was  filled  with  gold.  With  a  properly 
adjusted  electromagnetic  mallet,  carefully  guided,  and  operated 
with  a  full  current  of  electricity  from  a  freshly  charged  four-cell 
Bunsen  battery,  the  contour  of  each  crown  was  restored  with  gold, 
made  solid  and  perfect  throughout ;  the  foil  was  placed  in  the  same 
manner  over  the  finely  prepared  margins  of  enamel,  which  were 
not  marred  in  the  least  (Fig.  506). 

"  The  lower  incisor  teeth  had  so  changed  after  the  loss  of  the 
upper  lateral  that  they  almost  closed  upon  the  gum.  This  was 
partly  owing  to  the  abrasion  of  the  remaining  teeth,  and  in  part 
due  to  the  lower  incisors  gradually  rising  in  the  alveolar  process. 
Because  of  such  occlusions  of  the  teeth  a  porcelain  crown    (plain 


BRIDGE    DENTURES. 


559 


'  plate  tooth  ')  with  '  cross-pins  '  was  used,  and  fitted  .and  soldered  to 
the  gold  wire,  there  being-  no  space  for  a  backing  of  plate.  When  the 
wire  was  prepared,  the  porcelain  grooved  and  fitted  to  it,  and  ready 
for  the  placing  on  of  the  gold-foil,  the  whole  appeared  as  illustrated 
(Fig.  505),  the  wire  extending  into  each  adjoining  root  about  four 
lines.  The  cutting  edge  of  the  porcelain  was  removed  to  the  same 
extent  as  that  of  the  abraded  and  prepared  incisors,  so  as  to  present 
the  same  appearance  and  have  the  gold  support  and  protect  the  re- 
maining part.  The  wire  of  the  crown  was  held  in  a  hand-vise, 
while  cohesive  gold-foil  was  placed  solidly  in  the  grooves,  around 
the  wire,  over  the  cutting  edge  of  the  porcelain,  and  the  entire  con- 
tour restored  with  the  electromagnetic  mallet.  During  the  final 
fitting  of  the  crown,  it  was  made  to  so  rest  against  the  gum  that 
the   blood   was   pressed    from   the   capillaries    of   the   part.     When 

Fig.  506. 


ready  for  insertion,  a  medium  rubber  dam  was  applied  to  two  teeth 
each  side  of  and  across  the  space  which  was  to  receive  the  crown ; 
small  barbs  were  made  all  around  the  wire  with  a  sharp  knife,  and 
oxychlorid  of  zinc  was  then  placed  in  the  pulp  chamber  of  the  cen- 
tral incisor  and  cuspid,  and  the  crown  at  once  pressed  to  place. 
After  it  had  been  in  position  an  hour,  to  allow  of  complete  crystal- 
lization of  the  cement,  portions  of  this  and  of  the  dentine  were  re- 
moved with  a  small  bur  so  as  to  better  secure  the  crown  and  ob- 
tain anchorage  for  the  gold-foil  then  to  be  put  in  place  around  the 
wire,  into  each  cavity,  and  over  the  prepared  margins  of  the  enamel. 
Principally  No.  30  gold  (%  of  an  ounce  cohesive  foil)  was  used 
in  this  case,  and  all  was  impacted  with  the  electromagnetic  mallet, 
except  a  few  pieces  of  light  foil  placed  in  the  space  between  the 
wire  and  cervical  wall,  and  even  these  pieces  were  gone  over  with 
this  very  valuable  instrument  after  they  were  in  place.     With  this 


560 


MECHANICAL    DENTISTRY, 


and  all  the  operations  completed,  the  case  appears  as  illustrated  in 
Figs.  506  and  507. 

"  All  those  who  have  the  ability"  and  who  will  work  earnestly 
and  conscientiously  to  properly  perform  the  various  operations 
described,  and  .do  their  very  best  in  every  case,  can  so  manage  their 
practice  as  not  to  make  it  necessary  for  any  of  the  patients  they  have 
charge  of  to  wear  artificial  teeth  mounted  upon  plates." 

Dr.  W ebb's  method  of  operating  in  these  cases  was,  to  some  ex- 
tent, subsequently  modified  as  follows  : 

"  The  method,   modified  and   followed  by  the  writer   since  per- 


a,  b,  d,  f,  g,  and  h.  Pulpless  teeth,  g.  Whole  crown  restored  with  gold,  a,  f,  and 
h.  Almost  entire  gold  crowns.  The  teeth,  b  and  d,  support  the  gold  crown 
faced  with  porcelain,  c,  and  fully  one-fourth  of  the  crown  of  each  of  these  is 
restored  with  gold,  as  is  also  that  of  e,  the  pulp  of  which  is  living. 


forming  his  first  operation,  is  quite  different  from  the  mode  adopted 
in  inserting  the  first  crown,  which  was  prepared  somewhat  accord- 
ing to  Dr.  Bing's  plan,  and,  though  the  work  is  more  difficult,  yet 
the  improved  crown  is  stronger,  and  more  complete,  cleanly,  and 
beautiful  than  when  gold  plate  is  simply  riveted  and  soldered  to  the 
porcelain.  It  was  to  avoid  such  an  accident  as  the  breaking  of  the 
porcelain  from  the  pins  that  the  writer  modified  the  method  of  pre- 
paring and  inserting  crowns.  Among  the  changes  made  were 
those  of  making  a  groove    (though  not  cutting  it  too  deeply)    in 


BRIDGE   DENTURES. 


501 


each  side  and  along  the  cutting  edge  of  the  porcelain,  and  placing 
gold-foil  solidly  in  the  groove  and  slightly  over  the  cutting  edge, 
to  make  the  porcelain  more  secure  than  when  the  platinum  pins 
alone  hold  it,  and  to  protect  the  edge  from  the  occlusion  of  the 
lower  teeth;  also,  to  build  the  crown  into  the  approximal  surfaces 
only.  After  the  wire  has  been  fitted  to  the  adjoining  tooth  or  teeth, 
or  properly  placed  in  a  root,  and  a  heavy  but  rather  narrow  back- 
ing of  gold  plate  has  been  riveted  to  the  porcelain,  and  the  parts 
are  fixed  together  and  soldered,  the  greater  part  of  the  preparation  of 
a  crown  which  remains  to  be  made,  and  the  whole  of  the  building 
of  gold-foil  about  it,  is  done  out  of  the  mouth  at  whatever  time 
may  best  suit  the  operator;  but  the  work  requires  care,  and  must 
be  skilfully  and  well  done.  A  starting-point  should  be  made 
either  between  the  gold  backing  and  porcelain  or  between  this  and 
the  wire,  and  the  latter  must  be  firmly  fixed  in  a  hand-vise  while 
the  gold- foil  is  being  put  in  place  and  made  compact  with  the  electro- 
magnetic mallet.  All  crowns  should  be  prepared  and  finished  in 
the  manner  described,  with  such  change  or  additional  work  as  is 
necessary  to  place  them  on  roots,  or  to  attach  them  to  single  or  to 
the  two  adjoining  teeth  where  roots  are  missing. 

"  Methods  have  been  devised  or  adopted  with  the  object  of  les- 
sening the  time  necessary  to  perform  such  operations,  and  making 
them  easy  and  cheap,  by  the  use  of  amalgam  or  some  other  plastic 
material;  but  sufficient  time  must  be  taken,  excellent  judgment  and 
ability  are  required,  and  the  use  of  gold  is  necessary  for  the  doing 
of  really  fine,  beautiful,  and  permanent  work. 

"  When  a  crown  is  to  be  attached  to  one  tooth  alone,  the  opera- 
tion is  not  likely  to  be  successful  (excepting  where  a  bicuspid 
crown  is  built  into  a  molar  tooth),  unless  the  tooth  which  is  to 
support  the  crown  be  a  pulpless  one,  and  then  such  an  operation 
can  be  made  both  durable  and  beautiful.  To  secure  sufficient  an- 
chorage for  the  insertion  of  a  crown  in  such  a  manner,  therefore, 
it  may  sometimes  be  necessary  to  destroy  a  pulp;  but  this  ought 
to  be  the  last  resort,  and  should  be  done  only  when  calcification 
of  the  enamel  and  dentine  is  complete  or  apparently  so.  The  end, 
if  well  attained,  justifies  the  destruction  of  a  pulp  for  the  insertion 
of  a  crown,  mainly  because  of  the  beneficial  results  which  follow. 

"  Where  a  crown  is  to  be  built  on  to  one  tooth  only,  a  gold  wire 
no  lighter  than  No.  12  should  be  used.  It  should  be  fitted  as  far 
36 


562  MECHANICAL  DENTISTRY. 

up  the  root  as  it  is  safe  to  enlarge  the  pulp  chamber  for  it;  but 

the  drilling  may  be  properly  done  only  after  every  part  of  the  pulp 

has    been    removed    and    the    apical    foramen    has    been    carefully 

closed  with  small,  narrow  pieces  of  light  gold-foil,  which  must  not 

be  put  in  place  so  long  as  there  is  any  irritation  about  the  end  of 

the  root. 

"  In  the  case  here  illustrated  (Fig.  508),  the  wire  is  fitted  in  the 

root   and   bent   to   receive  the   crown,   and   the   cavity   is   prepared 

for  the  filling  in  of  gold.     The  cuspid,  as  well  as  the  other  teeth 

remaining    in    the    mouth,    became    so    abraded    as    to    expose    the 

dentine,  so  that  the  margins  of  enamel  had  to  be  prepared  for  the 

placing  of  gold  over  them,  and  when  the  crown  was  built  in  place, 

they  were  carefully  covered  with  and  are  thus   protected  by  the 

solid  metal.     After  the  porcelain  part  of  the  crown  of  the  lateral 

incisor  had  been  fitted  to  the  model  and 
Fig.  508. 

soldered  to   the  wire — this   portion  of 

the  wire  should  be  flattened  somewhat 

in  some  cases — the  groove  was  made 

around  the  porcelain ;  the  foil  was  solidly 

built  in  place,  and  finished  in  the  manner 

hereinbefore  described ;  the  crown  was 

then  inserted,   and  the  contour  of  the 

cuspid   tooth   was   restored   with   gold. 

The  root  of  the  left  central  incisor  remains,  and  the  crown  which  is 

fitted  upon  it  is  prepared  for  the  building  on  of  gold-foil;  after 

which  it  will  be  ready  for  insertion.     When  this  crown  is  put  in 

place,  the  gold  wire  is  to  be  surrounded  with  gutta-percha;  but 

little  of  which  is,  or  should  be,  needed  in  the  pulp  chamber,  because 

of  the  close  fitting  of  the  wire  in,  and  of  the  crown  upon,  the  root. 

During  this  preparation,  a  plain  pivot  crown  is  kept  upon  the  root, 

held  by  wood  and  gutta-percha. 

"  When   the   lateral   incisor   crown,   in   the   case   illustrated,   was 

ready  for  insertion,  and  the  gold  at  the  base,  which  was  to  rest 

upon  the  gum,  had  been  nicely  fitted  to  it,  and  the  whole  of  the 

gold  was  smoothly  finished,  a  good-sized  piece  of  medium  rubber 

dam   was   applied   to  the   teeth    (the   cuspid   and   the  central   and 

lateral  incisors)  on  each  side  of  the  space  to  be  filled,  and  arranged 

so  as  to  cover  the  gum  and  the  ropt  between  these  teeth.     The 

crown  was  made  to  so  rest  upon  the  gum  as  to  press  the  blood 


BRIDGE   DENTURES.  563 

from  the  capillaries  of  the  part,  and  thus  prevent  particles  of  food 
from  getting  under  it.  (While  the  thickness  of  the  rubber  dam 
might,  to  some  extent,  prevent  the  placing  of  such  a  crown  against 
the  gum  as  firmly  as  it  should  be  pressed,  yet  this  thickness  is 
compensated  for  by  the  pressing  up  of  the  gum  when  the  floss-silk 
ligatures  are  placed  about  the  neck  of  each  adjoining  tooth.) 
After  all  this  had  been  done,  and  fine  barbs  were  cut  around  the 
gold  wire  with  a  sharp  knife-blade,  oxychlorid  of  zinc  was  placed 
in  the  pulp  chamber  of  the  cuspid  tooth,  and,  while  the  cement 
was  still  plastic,  the  crown  was  at  once  pressed  into  place,  and  held 
there  for  a  few  moments. 

"  After  the  cement  had  hardened  sufficiently  to  safely  admit  of 
it,  it  was  cut  away  from  around  the  wire  at  such  parts  as  would 
make  proper  anchorage  for  the  gold.  There  was,  and  in  every 
case  should  be,  a  little  space  left  between  the  wire  and  cervical  wall 
to  be  filled  with  gold  for  the  protection  of  the  enamel  at  this  part. 
Narrow  pieces  of  light  cohesive  foil  were  first  placed  in  this  space 
with  small,  suitably  curved  instruments,  and  afterward  solidified 
with  the  mallet;  after  which  a  little  larger,  though  still  narrow,  and 
heavier  (none  over  No.  32)  pieces  of  folded  foil  were  used  for 
placing  around  and  about  the  wire  in  the  root,  filling  the  cavity, 
restoring  the  contour,  covering  and  protecting  the  prepared  mar- 
gins of  the  enamel,  each  piece  of  the  gold  being  thoroughly  cohesive 
and  made  compact  with  the  electromagnetic  mallet.  The  surface 
of  the  gold  placed  around  the  wire  between  it  and  the  cervical  wall, 
as  well  as  all  that  part  near  the  gum,  was  smoothly  finished  with 
small  files  and  very  narrow  (Jg  of  an  inch  wide)  strips  of  emery 
cloth  before  the  removal  of  the  rubber  dam;  after  which  the  re- 
mainder of  the  gold  was  made  smooth  and  so  trimmed  down  as  to 
be  sure  of  the  proper  occlusion  of  the  teeth.  The  crown  attached 
to  the  cuspid  tooth  was  made  just  short  enough  to  be  free  from  the 
striking  of  the  lower  teeth.  The  operation  was  finished  at  another 
time  with  Hindustan  stones,  together  with  pumice  upon  fine  wood 
made  into  suitable  shape. 

"  When  a  crown  can  be  securely  attached  to  one  instead  of  two 
teeth,  the  time  of  building-in  is  lessened  about  one-half.  The 
slight  movement  which  takes  place  in  the  socket  of  the  tooth 
supporting  the  crown  is  not  so  interfered  with  as  when  two  teeth 
are  fixed  together  by  the  gold  wire  holding  the  porcelain.     If  it 


564 


MECHANICAL    DENTISTRY. 


should  afterward  become  necessary  to  perform  operations  upon 
the  adjoining  teeth,  the  rubber  dam  can  as  readily  be  applied  as 
before  attaching  the  crown." 

Dr.  Darby's  Method. — Professor  E.  T.  Darby,  in  commenting 
on  the  method  just  described,  says :  "  Dr.  B.  J.  Bing  was  the  first  to 
call  my  attention  to  a  method  of  building  one  tooth  into  the  adjoin- 
ing teeth  by  means  of  gold  wires  running  from  the  artificial  into 
the  natural  teeth.  I  have  never  seen  any  of  Dr.  Bing's  operations, 
but  Dr.  Marshall  H.  Webb  has  called  my  attention  to  one  or  more 
in  the  mouths  of  his  patients,  which  have  done  good  service  for 
years.  I  also  have  in  my  own  practice  several  of  which  have  proved 
most  satisfactory. 

"The  cuts,  Figs.  509  and  510,  represent  two  cases  where  arti- 


Fig.  509. 


Fig.  510. 


ficial  crowns  have  received  their  support  from  the  adjoining  teeth. 
It  is  desirable  to  have  a  pulpless  tooth  for  a  neighbor,  though  I 
question  if  one  would  be  justified  in  devitalizing  a  pulp  to  secure 
this  end.  In  the  cases  presented,  a  piece  of  gold  wire  was  soldered 
to  the  backing  of  the  porcelain  tooth,  and  allowed  to  extend  well 
up  the  pulp  canal  of  one  of  the  adjoining  teeth.  After  it  had  been 
nicely  fitted  to  its  place,  the  rubber  clam  was  applied  and  drawn 
tightly  over  the  gum  between  the  two  natural  teeth ;  the  canal  of 
the  devitalized  tooth  was  then  filled  with  oxychlorid  of  zinc  and  the 
tooth,  with  its  gold  support,  pressed  into  position.  When  the  cement 
had  hardened,  the  bulk  of  it  was  cut  out  and  the  space  filled  thor- 
oughly with  gold.  The  other  end  of  the  bar  was  packed  around 
with  gold-foil,  and  the  cavity  of  decay  or  cavity  of  convenience  was 
filled  in  the  ordinary  way. 


BRIDGE   DENTURES. 


565 


"  It  is  always  better  to  take  an  impression  of  the  space  and 
adjoining  teeth  at  the  outset,  and  then  do  the  major  part  of  the 
work  in  the  laboratory.  The  gold  wire  which  enters  the  root  can 
be  bent  or  shaped  with  the  pliers  when  the  crown  is  adjusted  for 
final  insertion. 

"  I  would  not  be  understood  as  saying  that  these  operations  can 
only  be  performed  successfully  where  there  is  a  devitalized  tooth 
for  a  neighbor;  on  the  contrary,  I  have  seen  teeth  inserted  in  this 
way  where  both  teeth  were  living,  but  the  support  which  is  to  be 
derived  from  the  long  right  angle  of  gold  in  the  root  is  certainly  a 
great  security  against  accident,  adding,  as  it  must,  much  strength 
to  the  operation." 

The  Plate  and  Pin  Bridge. — Professor  Wilbur  F.  Litch  has 
greatly  improved  and  simplified  the  method  of  attaching  a  single 

Fig.  51 1. 


crown  to  the  adjoining  teeth  in  the  class  of  cases  under  considera- 
tion.    The  following  is  his  description  of  the  process : 

"Fig.  511  represents  a  typical  case,  in  which  a  lateral  incisor 
(crown  and  root)  has  been  lost,  the  cuspid  and  front  incisor,  fully 
vitalized  and  without  approximal  carious  cavities,  remaining  in  posi- 
tion. 

"  1.  Take  in  plaster  an  accurate  impression  of  the  cuspid  and 
incisor  and  the  interspace.  From  this  obtain  a  plaster  model  of 
the  parts. 

"  2.  Make  from  pure  gold,  rolled  to  the  thinness  of  26,  standard 
gage,  base-plates,  to  be  carefully  adjusted  to  the  palato-approxi- 
mal  surfaces  of  the  cuspid  and  incisor.  These  can  be  made  by 
swaging  on  dies  and  counter-dies  obtained  from  the  model,  but  more 
conveniently  by  bending  the  gold  into  shape  upon  the  plaster  model 
and  pressing  and  burnishing  it  into  perfect  adaptation  upon  the 
natural  teeth. 


5  66  MECHANICAL   DENTISTRY. 

"  3.  Select  a  plain  plate  porcelain  tooth  of  suitable  length,  shape, 
and  shade,  and  wide  enough  to  fit  easily  into  the  interspace.  Let 
the  neck  of  the  tooth  rest  lightly  upon  the  gum. 

"  4.  With  pure  gold  or  platinum  make  a  backing  for  the  porce- 
lain tooth. 

"  5.  Place  the  tooth  thus  prepared  and  the  base-plates  already 
made  upon  the  cast,  and  accurately  adjust  the  approximal  edges  of 
the  base-plates  to  the  backing  of  the  porcelain  tooth  in  situ  upon  the 
cast. 

"  6.  When  this  adjustment  is  made,  cement  together  the  base- 
plates and  backing  with  a  brittle,  resinous  cement  (resin,  two 
parts;  wax,  one  part;  or  sealing-wax  will  answer),  and  before  the 
cement  has  fully  hardened  remove  from  the  cast  to  position  in  the 
mouth,  perfecting  the  final  adjustment  there.  By  this  method  much 
greater  accuracy  of  adaptation  is  obtained,  as  the  lines  of  length, 
width,  and  contour  are  too  fine  to  be  reproduced  with  absolute 
fidelity  in  a  plaster  model.  In  this  part  of  the  process  too  much 
care  cannot  be  taken  to  have  each  piece  of  the  appliance  fitted  with 
absolute  accuracy  to  the  surface  for  which  it  is  designed.  When 
this  has  been  accomplished,  throw  upon  the  yet  more  or  less  plastic 
cement  a  stream  of  ice-cold  water  from  an  office  syringe;  this  ren- 
ders the  cement  perfectly  brittle  and  incapable  of  bending.  Imme- 
diately remove  from  the  mouth  and  invest  in  a  mixture  of  equal 
parts  of  marble-dust  and  plaster-of-Paris. 

"  7.  After  the  investment  has  firmly  set,  solder  the  base-plates 
to  the  backing,  and  the  backing  to  the  platinum  pins  of  the  porce- 
lain tooth,  using  as  a  solder  20-carat  gold.  Thus  joined,  the  appli- 
ance will  present  the  appearance  shown  in  Fig.  515.  A  represent- 
ing the  base-plate  for  the  cuspid ;  B,  the  base-plate  for  the  incisor ; 
C,  the  porcelain  tooth  with  its  platinum  backing;  D,  the  points  of 
union  between  the  base-plates  and  backing.  At  these  points  the 
greatest  strength  is  required,  and  it  is  important  that  here  a  large 
amount  of  the  solder  should  be  placed.  The  porcelain  tooth  being 
usually  thinner  than  the  natural  teeth,  there  is  nearly  always  an 
angle  or  depression  at  the  points  indicated,  in  which  the  thickness 
of  the  gold  can  be  considerably  increased  without  interfering  with 
occlusion. 

"  8.  For  the  purpose  of  attaching  the  denture  as  thus  far  con- 
structed, drill  a  small  cylindrical  opening  through  the  palatal  stir- 


BRIDGE   DENTURES.  567 

face  of  the  enamel  of  the  cuspid  and  incisor  respectively.  These 
openings  should  usually  be  placed  about  as  indicated  in  Fig.  514, 
at  C,  D.  Sometimes,  owing  to  a  close  occlusion,  or  to  the  con- 
tour of  the  tooth,  it  is  desirable  that  they  should  be  located  a  trifle 
nearer  the  neck  of  the  tooth.  Each  opening  should  be  well  under- 
cut, but  must  not  encroach  upon  the  dentine  far  enough  to  endanger 
the  pulp.  In  size  the  openings  need  not  be  larger  than  will  admit 
a  platinum  pinhead,  in  diameter  corresponding  to  13,  standard  gage, 
with  a  shank  of  18,  standard  gage.  Into  each  of  these  openings 
must  be  fitted  a  platinum  pin  of  the  size  indicated.  The  head  of 
each  pin  must  be  made  thin  and  perfectly  flat  both  upon  its  upper 
and  under  surfaces. 

"  9.  In  each  of  the  base-plates  make  an  opening  corresponding 
in  position  to  those  in  the  natural  teeth.  Pass  through  these  open- 
ings   and    cement   in    them    the    free    ends    of    the    platinum    pins. 

Fig.  512.  Fig.  513. 


While  the  cement  is  yet  plastic,  place  the  denture  in  position  in 
the  mouth,  carefully  pressing  the  pinheads  into  the  openings  made 
for  them  and  burnishing  the  base-plates  into  perfect  contact  with 
the  palatal  surfaces  of  the  teeth;  chill  the  cement,  remove  and 
invest  as  before,  and  with  20-carat  gold  solder  the  pins  to  the  base- 
plates, flowing  upon  them  and  the  backing  as  much  of  the  solder 
as  may  be  necessary  to  give  them  the  desired  thickness  and  rigidity ; 
the  amount  admissible  largely  depending  upon  the  nature  of  the 
occlusion,  a  central  thickness  of  about  21,  standard  gage,  being  all 
that  is  really  requisite  for  strength,  while  the  edges  can  be  made 
much  thinner. 

"Fig.  512  represents  the  appliance  without  the  pin.  A  is  the 
porcelain  tooth  and  backing ;  E,  the  base-plates ;  C  and  F,  the  open- 
ings for  the  pins. 

"Fig.  513  represents  the  appliance  completed,  with  the  pins  in 
position. 


568 


MECHANICAL    DENTISTRY. 


"  Fig.  514  represents  the  natural  teeth  and  interspace  B,  with 
openings  for  retaining  pins,  C,  D. 

"Fig.  515,  already  described,  represents  the  appearance  presented 
when  the  bridge  is  cemented  in  position. 

"  To  Attach  the  Bridge. — To  attach  the  bridge  the  best  attainable 
oxyphosphate  cement  should  be  used.  It  is  desirable  that  it  should 
set  slowly.  Thoroughly  dry  the  teeth  and  denture;  mix  the  cement 
to  as  thick  a  consistency  as  is  compatible  with  perfect  plasticity. 
A  thick,  viscid,  semi-fluid  mass  is  what  is  required.  With  suitable 
instruments,  swiftly  but  carefully  place  the  cement  around  the  head 
and  shank  of  each  platinum  pin,  and  also  in  the  openings  in  the 
natural  teeth.  This  care  is  necessary  in  order  to  exclude  all  the 
air-bubbles  and  thoroughly  engage  the  pinheads  in  the  cement. 
They  furnish  ample  retaining  surface,  but  none  to  spare.     In  pack- 


Fig.  514. 


ing  the  cement  around  the  pins,  the  under  surface  of  the  base-plates 
should  at  the  same  time  be  covered. 

"  The  above  details  being  perfected,  the  denture  is  at  once  car- 
ried to  position,  and  with  broad-pointed,  serrated  instruments 
pressed  firmly  into  place,  the  excess  of  cement,  if  of  the  proper  con- 
sistency, freely  oozing  at  all  margins. 

"  Too  much  care  cannot  be  exercised  in  the  cementing  process. 
As  every  second  of  time  is  of  value,  all  instruments  required  must 
be  selected  and  conveniently  placed  before  the  oxyphosphate  is 
mixed.  To  secure  the  most  rapid,  and  at  the  same  time  thorough, 
admixture  of  the  phosphoric  acid  and  zinc  oxid,  a  thick  plate-glass 
slab,  four  inches  square,  with  a  flat  (not  a  concave)  surface  should 
be  used.  The  spatula  should  be  of  steel,  thin  and  elastic,  and  ^  of 
an  inch  wide.  With  these  implements  the  whole  mass  of  cement, 
acid,    and    oxid    can    almost   instantly   be   brought   into   union,    the 


BRIDGE   DENTURES.  569 

spatula  being  used  as  a  muller.  When  a  narrow  and  rigid  spatula 
is  used  in  mixing  any  considerable  amount  of  oxyphosphate,  the 
process  can  be  accomplished  only  in  detail,  portion  by  portion,  much 
valuable  time  being  thus  lost,  during  which  the  setting  process  is 
every  moment  hastening  to  its  completion-  and  rendering  the  cement 
unfit  for  use  in  this  or  any  other  form  of  bridge-work.  A  large 
excess  of  acid  will,  of  course,  make  a  thinner  and  more  slowly 
setting  mass,  but  a  cement  thus  mixed  is  deficient  in  strength  and 
too  unstable  to  give  good  results. 

"  A  very  troublesome  obstacle  to  success  in  the  use  of  the 
oxyphosphate  cements  will  often  be  found  in  the  temperature  of 
the  air,  an  elevated  temperature  so  hastening  those  chemical 
changes  upon  which  the  hardening  of  these  cements  depends  as 
to  render  their  use  almost  impracticable.  This  difficulty  is  likely 
to  occur  only  in  the  hotter  seasons  of  the  year,  and  can  readily  be 
overcome  by  placing  the  mixing  slab,  as  well  as  the  acid  and  oxid 
bottles,  in  cold  water  until  their  temperature  has  been  considerably 
reduced. 

"  During  severe  winter  weather  too  low  a  temperature  also  gives 
trouble,  the  acid  and  oxid,  even  when  the  former  is  in  some  excess, 
forming  a  powdery  mass  utterly  unworkable,  but  which  melts  down 
into  an  almost  fluid  condition  when  brought  into  contact  with  the 
warmth  of  a  tooth  in  situ.  A  temperature  between  6o°  and  65 °  F. 
secures  the  best  results  in  mixing  oxyphosphate  cements. 

"  Application  to  Piilpless  Teeth. — In  the  above  description  the 
vitality  of  the  cuspid  and  incisor  has  been  assumed;  but,  as  can 
readily  be  understood,  the  pin  and  plate  bridge  can  be  even  more 
readily  and  securely  placed  when  one  or  both  pulps  are  devitalized, 
for  the  reason  that,  the  pulp  chamber  being  empty,  the  pinholes 
in  that  tooth  can  be  made  as  much  larger  and  deeper  as  may  be 
deemed  desirable,  the  size  of  the  pin  being,  of  course,  correspond- 
ingly increased.  In  a  devitalized  tooth,  too,  the  base-plate  can  be 
sunk  into  the  palatine  surfaces  when  they  interfere  with  occlusion, 
as  sometimes  happens  when  the  antagonism  of  the  lower  teeth  is 
very  close  and  the  overlap  is  considerable. 

"  Ordinarily,  however,  such  interference  is  considerable,  and  the 
difficulty  can  always  be  overcome  either  in  devitalized  teeth  by  the 
expedient  just  suggested,  or  by  carrying  the  base-plates  as  far 
away  from  the  cutting  edge  as  practicable,  at  the  same  time  mak- 


5/0 


MECHANICAL   DENTISTRY. 


ing  them  at  the  point  of  contact  as  thin  as  is  consistent  with  strength ; 
finally,  if  necessary,  removing  a  slight  portion  of  the  cutting  edge 
of  the  occluding  lower  tooth. 

"  As  experience  with  this  as  well  as  other  forms  of  bridge- work 
has  fully  demonstrated,  a  slight  mutilation  of  a  natural  tooth  is  far 
less  destructive  in  its  ultimate  results  than  is  the  wearing  of  partial 
plates,  in  the  use  of  which  pressure  falls  upon  the  gum  tissue,  with 
the  ultimate  effect  of  stripping  it  from  around  the  necks  of  the 
natural  teeth,  thus  denuding  them  of  that  protective  covering,  and 
exposing  them  to  the  ravages  of  decay,  and  it  may  be  safely 
affirmed  that  in  all  applicable  cases  the  pin  and  plate  bridge  ac- 
complishes its  purpose  with  the  minimum  of  injury  to  the  natural 
organs. 

"  The  small  size  of  the  retaining  pins  may  excite  doubts  as  to 
the  strength  of  the  denture ;  but  pins  smaller  in  size  are  constantly 
used  for  attaching  porcelain  teeth  to  plates,  and  in  the  upper  in- 
cisors these  pins  are  much  less  advantageously  placed  for  resist- 
ance to  pressure  than  are  those  imbedded  in  the  natural  teeth  in  the 
process  above  described. 

"  The  weakest  point  in  the  bridge  is  not  the  pins,  but  the  cement ; 
this,  while  not  so.  strong  as  the  fused  porcelain  which  surrounds  the 
pins  in  artificial  teeth,  is,  as  experience  has  demonstrated,  just  strong 
enough  to  resist  all  ordinary  wear  and  tear,  without  being  so  in- 
tractable as  to  render  the  removal  of  the  denture  for  purposes  of 
repair  a  practical  impossibility  by  any  method  short  of  its  destruc- 
tion. 

"  Even  with  a  good  oxyphosphate  cement,  the  work  of  removal 
is  one  of  no  slight  difficulty,  and  requires  the  exercise  of  so  con- 
siderable an  amount  of  force  that  no  one  who  has  had  occasion  to 
perform  that  operation  will  question  the  security  of  any  well- 
constructed  specimen  of  this  form  of  bridge.  During  an  experi- 
ence of  some  seven  or  eight  years  in  their  use,  the  writer  has  had 
but  one  or  two  cases  in  which  the  appliance  became  loosened,  and 
only  one  in  which  it  was  detached  outright.  In  the  latter  case 
the  bridge  (constructed  with  the  natural  tooth  of  the  wearer  in- 
stead of  a  porcelain  substitute)  had  been  firmly  in  position  for 
more  than  a  year,  when  the  sudden  wrench,  consequent  upon 
biting  into  a  very  hard  peach,  detached  it.  Being  immediately 
replaced,  it  has  since  then  done  good  service.     In  such  cases  it  is 


BRIDGE   DENTURES.  57I 

usually  advisable  to  slightly  deepen  the  undercuts  in  the  pinholes 
before  replacing. 

"  Repairing. — As  in  all  other  forms  of  bridge-work  in  which 
porcelain  teeth  are  used,  the  accident  most  likely  to  happen  is  the 
fracture  of  this  brittle  material.  As  the  bridge  does  not  yield 
under  pressure  as  does  a  detached  plate,  resting  upon  the  compres- 
sible gum  tissue,  this  form  of  breakage  is  one  to  which  bridge- 
work  is  more  than  usually  liable.  For  the  pin  and  plate  bridge, 
the  least  difficult  method  of  repair  is  to  separate  the  tooth  and 
backing  from  the  base-plates  by  means  of  a  watch-spring  saw,  and 
then  force  off  the  base-plates  singly,  this  being  much  more  easily 
accomplished  than  their  removal  when  united  to  the  backing. 
Another  tooth  is  then  selected,  fitted,  backed,  and  soldered  as 
before. 

"  As  a  rule,  the  writer  has  confined  the  use  of  this  form  of 
bridge  to  cases  in  which  only  a  single  incisor  is  missing,  but  he 
lias  successfully  attached  a  front  and  lateral  incisor  to  a  cuspid 
and  the  remaining  front  incisor.  When  an  unusual  strain  is  to  be 
expected,  the  retaining  pins  and  pinholes  should,  when  practicable, 
1}e  made  correspondingly  large,  or  two  smaller  pins  may  be  an- 
chored in  one  tooth,  which  latter  plan  gives  very  great  resisting 
power,  and  renders  removal  in  the  highest  degree  difficult  and 
laborious."  Prof.  Litch  informs  us  that,  for  his  more  recent  opera- 
tions of  this  class,  he  has  adopted  the  method  of  using  one  plate 
only;  that  is,  making  the  attachment  to  one  of  the  adjoining  teeth, 
iDUt  uses  in  this  two  small  retaining  pins,  one  of  them  being  placed, 
say,  near  the  cutting  edge  on  the  mesial  side  and  the  other  on  the 
distal  side  near  the  palatal  edge  of  the  plate.     (See  Fig.  511.) 

Under  this  head,  plate  and  pin  bridges,  may  properly  be  classed  a 
process  of  replacement  described  by  Prof.  Litch  in  connection  with 
the  "  pin  and  plate  attachments  "  as  a  means  of  support  for  single 
front  teeth,  a  method  of  attachment  which,  he  says,  although  chiefly 
applicable  to  the  incisors,  may  be  combined  with  crown  or  bar 
bridges  for  molars  and  bicuspids. 

"Fig.  516  represents  a  practical  case  in  which  the  upper  third 
molar  and  first  bicuspid  (both  without  antagonizing  teeth)  were 
utilized  for  the  attachment  of  a  bridge  made  of  gold  crowns  with 
porcelain  facings,  to  supply  the  loss  of  the  intervening  teeth. 

"  Fig.   517  represents  the  case  as  prepared   for  the  bridge.     A, 


572 


MECHANICAL   DENTISTRY. 


the  inner  cusp  of  the  bicuspid  cut  down  to  allow  the  placing  of  a 
sufficiently  thick  crown-plate ;  B,  a  cylindrical  undercut  opening 
between  the  cusps  for  a  retaining  pin ;  C,  the  third  molar  made 
uniform  in  size  from  neck  to  grinding  surface,  the  latter  also  being 
considerably  retrenched ;  D,  the  crown-plate  of  a  partial  cap,  made 
of  pure  gold,  soldered  with  20-carat  gold,  and  so  constructed  as 

Fig.  516. 


to  cover  every  portion  of  the  tooth  except  its  buccal  surface,  the 
free  edge  passing  up  under  the  gum;  E,  a  retaining  pin  adapted  to> 
the  opening,  B ;  F,  the  gold  cap  for  the  molar. 

"  Fig.  518  represents  the  bridge  anchored  in  position  with  oxy- 
phosphate  cement. 

"  In  the  above  case  it  will  be  observed  that  there  is  a  cons.ider- 


Fig.  517. 


able  space  between  the  bicuspid  and  cuspid.  This  made  it  readily 
practicable  to  give  so  considerable  a  thickness  to  the  mesial  waif 
of  the  partial  cap  as  to  hold  it  securely  against  the  side  of  the  tooth. 
Had  the  space  been  less,  contact  with  the  cuspid  would  have  afforded 
the  desired  security. 

"  Fig-    5T9   represents   another   case   in   which    a   bridge   was   at- 


BRIDGE   DENTURES. 


573 


tached  by  a  bar,  partial  cap,  and  retaining  pin.  A  is  an  upper  sec- 
ond bicuspid,  without  antagonist;  B,  its  inner  cusp  cut  down;  C, 
opening  for  retaining  pin ;  D,  second  molar,  with  slot  for  bar ;  E, 
cuspid;  F  represents  the  partial  facing;  G,  the  retaining  pin;  H, 
a  molar  crown  of  gold,  with  porcelain  front;  I,  a  platinum  bar  at- 


Fig.  518. 


Fig.  519. 


Fig.  520. 


,;: :___...  _ 


tached  to  the  crown  (H)  and  made  to  fit  into  a  slot  (at  D)  ;  J,  a 
plain  plate  cuspid,  heavily  backed  and  strongly  soldered  to  the 
partial  cap,  but  left  without  attachment  to  or  contact  with  the 
cuspid. 

"  Fig.  520  shows  the  bridge  anchored  in  position. 


574  MECHANICAL   DENTISTRY. 

"  This  case,  after  two  years  of  wear,  is  still  in  perfect  condition 
and  doing  good  service.  As  it  was  possible  to  keep  the  gold  at- 
tachments, backings,  etc.,  out  of  sight,  the  appearance  presented 
is  very  natural. 

"The  bridge  shown  in  Fig.  518  has  been  in  use  but  a  few 
months. 

"  The  absence  of  antagonizing  teeth  for  the  bicuspids  in  each  of 
these  cases  was  a  favorable  condition,  as  a  considerable  thickness 
could  be  given  to  the  crown-plate  without  any  interference  with 
occlusion.  When  the  conditions  are  not  so  favorable,  cutting 
down  the  inner  cusp  to  the  required  extent  and  sinking  the  open- 
ing for  the  retaining  pin  to  the  necessary  depth  are  processes  cer- 
tainly to  be,  as  a  rule,  preferred  to  the  entire  removal  of  the  crown 
for  the  purpose  of  ferruling  the  root  for  the  mounting  of  a  crown 
of  gold  and  porcelain — a  procedure,  however,  not  by  any  means  to 
be  indiscriminately  denounced,  for  in  many  cases  it  is  in  the  high- 
est degree  advisable. 

"  There  is  this  fact  to  be  considered  in  regard  to  the  use  of  the 
partial  caps  here  figured — that  many  patients  can  be  induced  to 
consent  to  their  employment  who  would  refuse  to  submit  to  more 
radical  measures,  and  thus,  even  when  the  latter  would  be  advis- 
able, the  former  may  be  employed  as  a  compromise,  or  even  as  a 
temporary  expedient.  Having  once  tested  the  advantage  of  a  well 
fitting  bridge,  the  wearer  is  much  more  likely  to  consent  to  what- 
ever measures  are  necessary  to  give  it  security  and  permanence. 

"  In  the  cases  figured,  however,  as  well  as  in  analogous  cases,- 
these  qualities  seem  to  be  amply  secured.  In  every  instance  in 
which  the  removal  of  a  pin  and  plate  bridge  has  been  necessary, 
the  film  of  oxyphosphate  cement  has  been  found  intact,  and  the 
surface  of  the  tooth  upon  which  it  rested  perfectly  protected  from 
decay.  The  only  exceptions  to  this  rule  have  been  the  very  few 
cases  in  which  one  or  the  other  of  the  retaining  pins  has  become 
loosened,  the  bridge  being  for  some  weeks  still  worn  in  the 
loosened  condition.  Under  such  circumstances  the  cement  will,  of 
course,  become  detached  and  wash  out,  admitting  food  and  secre- 
tions; but  so  long  as  the  appliance  remains  immobile — and  that  is 
its  normal  state — the  cement  rests  undisturbed.  It  need  hardly 
be  claimed  that  its  durability  is  without  limit,  although  under  a 
metallic   covering   it   appears   to   be   practically   so;   but   under   the 


BRIDGE   DENTURES. 


575 


conditions  represented  in  the  processes  as  above  described,  it  is 
certainly  good  for  many  years  of  satisfactory  service,  and  when  it 
fails,  through  chemical  abrasion,  it  will  fail  first  at  the  free  margins, 
where  defects  are  most  easily  seen  and  remedied." 

Dr.    Register's    Method. — The    following    is    a    condensed    ac- 

Fig.  521. 


Fig.  522. 


count,  by  Dr.  Dexter,  of  a  method  of  bridging  devised  by  Dr.  H. 
C.  Register,  one  of  the  earliest  experimenters  in  this  method  of 
replacement.  The  distinctive  feature,  as  also  the  special  merit,  of 
Dr.    Register's   appliance   consists   in    the   provision   made   for   the 


576  MECHANICAL  DENTISTRY. 

ready    replacement    of    broken    crowns.     The    process    is    thus    de- 
scribed : 

"Taking  a  typical  case  (Fig.  521),  a  rim  or  saddle  of  gold, 
platinum,  or  iridinized  platinum  is  struck  to  fit  the  spaces  between 
the  teeth  A  and  B.  To  this  are  attached  bars  X  (Fig.  523),  to 
enter  the  fillings  at  Z  Z  (Fig.  522).  Posts  or  pivots  (D,  Fig.  523) 
are  soldered  upon  this  saddle  where  the  artificial  teeth  are  to  be 
placed,  their  free  ends  being  threaded  to  carry  the  nut  E.  Hollow 
crowns,  countersunk  for  the  nut  at  G,  and  having  the  necks 
ground  to  reach  over  the  saddle  and  press  upon  the  gum,  are  fitted 
over  each  post.  Amalgam  is  used  to  fill  in  the  space  between  the 
post  and  the  tooth  wall,  as  in  a  Bonwill  setting,  and  the  crowns  are 
drawn  to  place  and  held  with  the  nut.  The  saddle  is  fixed  in  its 
place  in  the  mouth,  before  the  crowns  are  finally  attached,  by  filling 
into  the  cavities  Z,  the  bars  X  X." 


Dr.  Williams'  Method. — Dr.  J.  L.  Williams  has  given  to  the 
profession  a  number  of  important  communications  relating  to 
bridge-work,  to  which  space  is  given  to  such  portions  only  as 
relate  more  especially  to  practical  details.  The  initial  portion  of 
the  following,  reproduced  from  the  Dental  Cosmos,  treats  also  of 
single  crown  replacement,  and  is  embodied  in  this  connection  as 
having  immediate  and  necessary  relation  to  subsequent  descrip- 
tions. 

The  following  are  Dr.  Williams'  descriptions  of  his  methods  of 
crown  and  bridge  replacement : 

After  the  end  of  the  root  has  been  properly  shaped  and  a  gold 
ferrule  or  band  fitted  to  it,  a  suitable  tooth  is  selected  and  backed 
with  pure  platinum,  or  pure  gold.  The  cervical  end  of  the  tooth 
is  ground  to  the  proper  position  on  the  front  bevel  of  the  cap;  all 
of  the  fitting  being  done  while  the  cap  is  in  position  on  the  root.  For 
detailed  directions  see  Richmond  ferrule  or  band  crown,  page  503. 

After  the  fitting  is  completed,  the  cap  is  removed  and  the  tooth 


BRIDGE   DENTURES. 


577 


attached  by  strong  resin  wax  and  again  placed  in  position  while 
the  wax  is  warm.  Any  slight  change  in  position  which  is  neces- 
sary can  then  be  easily  made.  The  tooth  and  cap  are  now  removed 
together,  invested,  and  united  at  the  back  by  solder.  It  is  well  to 
use  a  solder  for  the  cap  with  a  higher  melting-point  than  that 
used  for  the  backing,  as  it  obviates  the  danger  of  unsoldering  the 
band  when  the  backing  is  flowed  on.  After  finishing  and  polishing 
the  work,  the  end  of  the  root  is  made  perfectly  dry,  a  sufficient 
quantity  of  oxyphosphate  cement,  mixed  somewhat  thinner  than 
for  filling  purposes,  is  placed  in  the  enlarged  pulp  canal  and  also 
in  the  cap.  The  crown  is  then  carried  to  the  place  with  firm, 
steady  pressure,  and  held  a  few  minutes  until  the  cement  is 
sufficiently  hard  to  prevent  displacement.  The  surplus  cement 
which  has  oozed  out  around  the  band  should  be  carefully  removed, 
and  the  work  is  then  completed.     This  is  all  illustrated  in  Fig.  524. 


Fig.  524. 


The  bridge-work  is  simply  an  extension  of  the  crowns  over  spaces 
where  the  natural  teeth  have  been  lost. 

Fig.  525  was  drawn  from  a  model  of  a  case  in  practice.  In  this 
the  roots  of  the  centrals  are  shown  prepared  for  the  fitting  of  the 
bands,  the  laterals  having  been  extracted.  Single  crowns  are 
made  for  these  roots  precisely  as  described.  They  are  then 
temporarily  placed  in  position.  Laterals  are  selected,  backed, 
ground,  and  fitted  to  position.  The  laterals  are  then  attached  by 
means  of  strong  wax  to  the  centrals,  carefully  adjusted  in  the 
position  which  we  wish  them  to  occupy,  and  the  whole  removed 
in  an  impression  of  investing  material.  An  additional  quantity  of 
investment  is  mixed  and  poured  over  the  exposed  ends  of  the  caps, 
and  the  whole  allowed  to  harden,  after  which  the  investing  material 
is  cut  away  from  the  backs  of  the  teeth  and  crowns,  when  they 
should  all  be  united  by  soldering. 

37 


5/3 


MECHANICAL   DENTISTRY. 


Fig.  526  shows  the  work  completed,  and  Fig.  527  is  from  a 
model  of  the  mouth  as  restored  with  the  crowns. 

In  cases  where  the  space  is  occasioned  by  the  loss  of  more  than 
one  tooth  a  somewhat  different  method  of  procedure  is  necessary. 

Fig.    528    shows    a   model    of    a   mouth    in    which    the    superior 


laterals  and  centrals  had  been  extracted.  The  canines  were  badly 
decayed,  with  exposure  of  the  pulp.  The  first  step  is  the  removal 
of  the  pulps  from  the  canine  roots.  The  crowns  are  then  fitted  as 
already  described  and  placed  in  position.  An  impression  is  taken 
in  plaster,   the  crowns   remaining  imbedded  on  its   removal.     The 


Fig.  526. 


Fig.  527. 


impression  is  varnished  and  oiled,  and  a  model  of  investing 
material  poured.  After  this  has  hardened,  the  impression  is 
carefully  cut  away,  and  we  have  a  model  of  the  mouth  with  the 
crowns  in  position.  A  bite  is  taken  and  the  articulation  se- 
cured in  the  usual   manner.     The  remaining  crowns,  having  been 


BRIDGE   DENTURES. 


579 


backed,  are  fitted,  and  the  face  of  the  work  imbedded  in  investing 
material. 

The  whole  piece  is  now  united  at  the  back  by  soldering,  and  when 
finished  presents  the  appearance  shown  at  Fig.  529. 


Fig.  528. 


Fig.  529. 


Fig.  530  shows  a  model  of  the  mouth  after  the  bridge  has  been 
cemented  in  place. 

Fig.  531  is  an  illustration  of  a  piece  of  this  work  for  which  there 

Fig.  530. 


is  a  very  frequent  demand.  It  is  for  supplying  the  loss  of  the  first 
molar  and  bicuspids.  If  the  cuspid  is  intact,  the  anterior  end  of 
the  bridge  may  be  attached  by  a  strong  band  of  clasp  metal  passing 


58o 


MECHANICAL   DENTISTRY. 


around  this  tooth,  partly  beneath  the  margin  of  the  gum,  so  as  to 
present  the  least  possible  exposure.  If,  as  is  frequently  the  case, 
there  is  extensive  decay,  it  will  be  best  to  excise  the  remaining  por- 
tion of  the  tooth  and  replace  it  with  an  artificial  crown  as  shown  in 
the  illustration.  The  latter  method  the  editor  believes  to  be  the 
better  practice,  even  where  the  cuspid  is  a  vital  tooth.  A  gold  cap 
is  then  made  for  the  second  molar.  If  this  tooth  is  decayed  it  will 
only  be  necessary  to  remove  the  decay,  and  the  cement  which  is  used 
for  setting  the  bridge  will  make  the  most  perfect  filling  material  be- 
neath the  gold  cap.  The  intervening  molar  and  bicuspid  crowns  are 
made  in  the  following  manner :   The  porcelain  faces  are  backed  with 

Fig.  531. 


gold  or  platinum  and  the  tips  ground  squarely  off.  Zinc  pattern  dies, 
an  assortment  of  which  should  be  made  from  the  grinding  surfaces  of 
molars  and  bicuspids,  are  used  for  swaging  from  pure  gold  a  tip  or 
cap  for  the  protection  of  the  porcelain  face ;  for  without  this  protec- 
tion the  porcelain  would  be  almost  certain  to  be  broken.  The  con- 
cave surface  of  these  tips  is  filled  by  melting  coin-gold  into  them. 
This  surface  is  then  ground  smooth  and  fitted  to  the  squared  surface 
of  the  porcelain  face  and  waxed  in  position.  Triangular  pieces  of 
platinum  are  then  cut  of  the  proper  size  to  fit  the  sides  of  the  tooth, 
waxed  in  position,  and  the  whole  invested,  leaving  the  back  open, 
which  is  filled  with  coin-gold.  The  several  surfaces  of  a  tooth  thus 
prepared  are  shown  in  Fig.  532. 


BRIDGE    DENTURES. 


581 


These  teeth  are  then  fitted  into  position  in  the  bridge,  as  previ- 
ously described. 

Fig.  534  shows  the  completed  work  in  the  mouth. 

Where  only  one  molar  or  bicuspid  is  lost,  sufficient  support  may 
be  gained  by  the  cap,  which  is  made  to  pass  over  the  adjoining 
molar.     If  the  first  molar  and  second  bicuspid  are  lost,  the  ante- 


Fig.  532. 


Fig.  533- 


rior  end  of  the  bridge  may  receive  sufficient  support  from  a  strong 
spur  (Fig.  533),  which  may  rest  in  the  groove  or  sulcus  between 
the  cusps  of  the  first  bicuspid ;  or  this  groove  may  be  deepened  into 
a  cavity,  into  which  the  spur  projects  and  around  which  a  filling  is 
placed. 

The  most   extensive   pieces   of   this   work   which   have   been   at- 


tempted are  cases  of  12  and  14  teeth  upon  three  and  four  roots. 
Several  of  these  have  been  worn  for  a  year  or  more,  and  none  of 
which  we  have  any  knowledge  shows  any  signs  of  failure. 

Perhaps  we  cannot  better  close  this  paper  than  with  the  descrip- 
tion of  the  restoration  of  a  mouth  where  any  attempt  to  remedy 


5§^ 


MECHANICAL    DENTISTRY. 


the  ruin  save  by  extraction  would  have  been  considered  madness ; 
and  yet  the  lady  for  whom  this  work  was  accomplished  is,  to-day, 
so  far  as  appearance,  utility,  and  comfort  are  concerned,  enjoying 
as  perfect  a  denture  as  any  person  who  has  the  same  number  of  nat- 
ural teeth  intact. 

Fig.  535  was  drawn  from  a  model  of  the  mouth  as  presented. 
Only  one  tooth  remained  the  pulp  of  which  was  not  exposed — 
the  left  second  superior  molar.  In  the  first  bicuspid,  cuspid,  and 
central  of  the  left  side  the  pulps  were  exposed  and  in  a  partially 
putrescent  condition.  Abscesses  had  formed  about  the  roots  of 
the  second  left  bicuspid,  right  central,  cuspid,  and  second  bicuspid. 

Fig.  535. 


The  pulp  was  slightly  exposed  and  inflamed  in  the  right  first  supe- 
rior molar.  The  second  bicuspid  on  the  right  side  and  both  bi- 
cuspids on  the  left  were  extracted  at  once  as  worthless.  The  ex- 
posed pulp  in  the  right  molar  was  treated  and  capped.  The  par- 
tially living  pulps  were  removed  from  the  teeth  above  mentioned, 
the  fistulous  openings  were  healed,  and  all  of  the  roots  thor- 
oughly cleansed,  and  plugged  with  orange- wood  saturated  with 
carbolic  acid  and  glycerin.  The  greatest  difficulty  was  encoun- 
tered in  the  treatment  of  the  right  cuspid  root,  which  had  two 
large  openings  through  the  side  of  it,  and  through  which  pro- 
jected into  the  enlarged  pulp  canal  a  tumefied  growth  of  the  peri- 


BRIDGE   DENTURES. 


533 


cementum.  For  several  weeks  the  tissues  around  this  root  were 
highly  inflamed,  and  the  face  was  several  times  badly  swollen. 
The  difficulty  was  finally  overcome  by  covering  these  openings 
with  No.  30  gold-foil  and  filling  the  root  with  amalgam.  Crowns 
were  then  fitted  over  all  of  the  roots.     A  bridge  was  then  extended 

Fig.  536. 


from  the  left  cuspid  to  the  first  molar  to  restore  the  lost  bicuspids. 
The  missing  bicuspid  on  the  right  side  was  restored  by  attaching 
the  crown  to  the  cap  which  was  placed  over  the  molar  containing 
the  exposed  pulp. 

Fig.  536  was  drawn  from  a  model  of  the  mouth  as  restored. 

Fig.  537  shows  a  piece  of  work  made  for  a  case  of  quite  fre- 


Fig.  537- 


quent  occurrence.  It  represents  the  restoration  of  the  inferior 
bicuspids  and  first  molar  of  the  right  side.  A  gold  crown  is  made 
for  the  second  molar,  and  then  the  three  intervening  teeth,  or 
"  dummies  "  are  made  as  has  been  previously  described.  For  the 
support  of  the  anterior  end  of  the  bridge  the  method  hitherto 
practised  has  been  to   excise  the  crown  of  the  cuspid  and  fit  a 


5§4 


MECHANICAL   DENTISTRY. 


porcelain  crown  with  gold  backing  to  the  root,  and  to  this  the 
anterior  end  of  the  bridge  is  soldered.  We  have,  however, 
in  Fig.  538  illustrated  a  device  which  obviates  the  necessity  for 
removing  the  cuspid  crown.  A  gold  band  is  fitted  around  the 
cuspid.  At  the  front,  shown  at  a,  this  band  is  allowed  to  pass  a 
little  beneath  the  margin  of  the  gum  so  as  to  make  the  smallest 
possible  exhibition  of  gold.  On  the  lingual  aspect  of  the  tooth 
this  band  is  allowed  to  be  nearly  the  length  of  the  crown.  It  will 
be  seen  that  when  this  band  is  fitted  as  perfectly  as  possible  there 
must  necessarily  be  quite  a  vacancy  between  the  upper  part  of  the 
lingual  surface  of  the  tooth  and  the  band.  It  is  important  that 
this  portion  of  the  band  fit  the  tooth  perfectly,  and  an  accurate 
adaptation  is  obtained  as  follows :  A  piece  of  pure  gold,  rolled  to 
No.  35  American  gage,  is  fitted  over  that  portion  of  the  lingual 

Fig.  538. 


surface  of  the  tooth  which  it  is  desired  to  cover,  d,  in  Fig.  538, 
shows  the  shape  that  this  little  pure  gold  plate  usually  assumes. 
It  can  easily  be  fitted  perfectly  by  the  use  of  a  burnisher,  and 
then,  with  the  band  in  position,  a  drop  of  melted  resin  wax  is 
flowed  into  the  space  between  the  pure  gold  and  the  band.  It  is 
now  removed  from  the  tooth,  invested,  and,  after  melting  out  the 
wax,  solder  is  flowed  into  the  vacancy,  filling  completely  the  space 
occupied  by  the  wax.  The  top  of  the  lingual  portion  will  now  be 
thicker  than  is  necessary,  but  can  be  easily  ground  or  filed  down  to 
the  proper  thickness.  We  now  have  a  band  which  fits  all  portions  of 
the  tooth  perfectly.  The  anterior  end  of  the  bridge  is  soldered  to 
this  band,  and  after  work  is  properly  finished  it  is  cemented  in 
place  in  the  usual  manner ;  /;  and  c  show  side  and  lingual  views 
of  this  band  after  the  fitting  is  completed. 

Another    device    for    obviating   the    necessity    for    removing    the 


BRIDGE    DENTURES. 


585 


crowns  of  natural  teeth  in  preparing  the  mouth  for  bridge-work  is 
illustrated  in  Fig.  539.  Crowns  are  fitted  in  the  mouth  to  the  points 
of  attachment  in  the  usual  manner.  An  impression  is  taken,  bring- 
ing the  crowns  away  in  their  proper  positions.     From  this  the  cast  or 

Fig.   539. 


model  is  obtained.  Heavy  bands  of  half-round  gold  or  platinum  bars 
are  now  fitted  around  the  necks  of  the  natural  teeth  on  their  lingual 
surfaces.  These  bands  being  waxed  in  position,  serve  to  connect 
the  different  parts  of  the  bridge,  uniting  them  in  one  piece  without 

Fig.  540. 


the  loss  of  any  of  the  natural  crowns.  This  has  been  found  a  highly 
satisfactory  method  of  inserting  extensive  pieces  of  bridge-work. 
Fig.  540  shows  the  mouth  as  presented  for  which  the  piece  shown 
was  constructed.     Fig.  541  shows  the  piece  in  position. 


;86 


MECHANICAL   DENTISTRY. 


Fig.  542  illustrates  a  case  which  is  a  type  of  a  class  of  frequent 
occurrence.  Alternate  molars  and  bicuspids  in  the  upper  and 
lower  jaws  are  lost,  until  the  occlusion  is  somewhat  changed,  and 

Fig.  541. 


Fig.    542. 


Fig.    543. 


Fig.  544. 


the  force  of  mastication  is  gradually  brought  upon  the  front  teeth. 
Rapid  wearing  of  these  teeth  results.  The  cases  are  among  the 
most    difficult    that    the    operator    is    called    upon    to    treat    by    the 


BRIDGE    DENTURES. 


587 


ordinary  methods.  In  the  case  herewith  illustrated,  the  lower 
bicuspids,  with  a  molar  on  one  side,  were  in  good  condition,  but 
the  loss  of  the  upper  bicuspids  and  molars  made  them  useless. 
As  usually  happens,  the  upper  incisors  had  suffered  most.  The 
lower  incisors  were  restored  by  capping  them  with  cohesive  foil. 
The  bridge  shown  in  Fig.  543  was  constructed  for  the  right  side 
of  the  upper  jaw,  while  the  teeth  on  the  left  side  were  restored  by 
contour  work,  as  shown  in  Fig.  544. 

The  superiority  of  the  condition  of  this  patient's  mouth,  which 
resulted  from  this  work,  over  anything  which  could  have  been  ac- 
complished by  plate-work,  is  almost  inconceivable  to  one  not  familiar 
with  these  methods. 

Dr.  Knapp's  Method. — After  constructing  the  crowns  as  di- 
rected  on  page  420,   suitable   plain   plate   teeth   should   be   backed 


Fig.  545. 


Fig.   547. 


Fig.   548. 


Fig.   550. 


Fig.    551. 


with  pure  gold  and  built  up  to  the  desired  shape  with  wax,  Fig. 

545,  which  should  be  incased  in  pure  gold  as  before  described,  Figs. 

546,  547,  and  548.  After  investing  and  subsequent  removal  of  the 
wax,  the  resulting  receptacle  can  readily  be  filled  with  20-carat  sol- 
der, Fig.  549. 

In  the  preparation  and  in  the  drilling  of  the  roots,  great  care 
should  be  exercised  to  have  the  caps  and  the  pins  as  nearly  paral- 
lel as  possible.  Here,  as  well  as  elsewhere,  sound  judgment  is 
essential  to  the  accomplishment  of  the  best  results.  For  the  at- 
tainment of  accuracy,  it  is  essential  that  an  impression  should  be 
taken,  preferably  in  plaster,  of  the  caps  in  their  proper  positions 
upon  their  several  roots.  An  impression  should  likewise  be  taken 
of  the  occluding  teeth.  The  models  obtained  from  these  impres- 
sions should  then  be  placed  in  an   articulator,   as   for  plate-work, 


;SS 


MECHANICAL    DENTISTRY. 


and  the  articulating  surfaces  of  the  porcelain  crowns  should  be 
carved  in  wax  to  a  nicety.  By  the  methods  just  mentioned  these 
occluding  surfaces  are  reproduced  in  gold.  The  requisite  exercise 
of  the  dental  organs  and  immunity  from  breakage  of  porcelain 
faces  are  in  this  way  secured.  The  porcelains  should  not  press 
upon  the  gums  except  in  the  anterior  portion  of  the  mouth,  where 
the  formation  of  the  alveolar  process  permits  and  the  perfection  of 
speech  demands  it.  The  gold  from  the  grinding  surfaces  should 
form  a  gradual  slope  until  it  reaches  the  porcelain,  and  should  be 
entirely  free  from  pits  and  other  irregularities.  When  they  occur, 
it  becomes  necessary  to  remedy  these  as  well  as  other  defects. 
This  is  to  be  done  by  the  refiring  of  either  a  single  crown  or  an 


Fig.  552. 


entire  piece  of  bridge-work.  At  times  gold,  where  needed,  may 
be  added  by  the  use  of  the  electric  mallet,  and  a  beautiful  finish 
obtained  with  it.  Under  all  circumstances,  both  porcelain  and  gold 
should  present  a  perfect  continuity  of  surface.  With  diligent  at- 
tention given  to  the  important  details  of  construction  which  are 
here  pointed  out,  the  great  bugbear  of  uncleanliness,  suggested  as 
an  objection  to  this  method  of  substitution,  is  entirely  removed. 
Of  course,  food  and  salivary  deposits  will  accumulate  around  ar- 
tificial crowns  as  well  as  about  natural  teeth,  and  the  personal 
cleanliness  of  the  wearer  is  the  greatest  and  indeed  sole  safeguard 
against  such  injurious  accretions  with  any  denture.  A  philosophy 
that  would  condemn  the  insertion  of  bridge-work,  artistically  con- 


BRIDGE    DENTURES. 


539 


stracted  on  scientific  principles,  on  the  score  of  uncleanliness,  would 
as  consistently  advise  the  extraction  of  the  natural  organs  for  the 
reason  that  their  possessor  was  a  sloven.  "  Cleanliness  is  next  to 
godliness,"  says  Wesley,  and  he  who  expects  to  wear  a  "  crown," 
here  or  hereafter,  must  heed  this  maxim. 

Fig.  550  shows  an  upper  central  and  lateral  incisor  mounted  upon 
a  central  root  with  spud  attachment.  Fig.  551  represents  the  four 
tipper  front  teeth  held  in  position  by  the  two  lateral  roots.  Fig.  552 
the  six  upper  front  teeth  mounted  upon  the  two  cuspid  roots.  Fig. 
553  represents  a  full  upper  denture  with  the  two  cuspid  roots  and 
two  molars  as  anchorages. 

For  the  attachment  of  crown-  and  bridge-work  the  best  obtain- 
able oxyphosphate  cement  should  be  used.  With  the  pins  notched, 
and  the  roots  perfectly  free  from  moisture,  sufficient  oxyphosphate 
should  be  placed  around  each  pin  and  inside  of  the  collar  to  com- 
pletely fill  all  the  space  between  the  pin  and  the  canal,  the  collar 
and  the  root.  Firm,  well-directed  pressure  should  then  be  exerted 
to  carry  the  piece  to  its  proper  position,  where  it  should  be  held 
for  a  few  minutes  to  permit  of  the  hardening  of  the  cement,  all 
excess  of  which  oozing  through  at  the  edge  of  the  collar  should 
"be  carefully  removed.  Before  being  dismissed,  the  patient  should 
be  instructed  to  be  a  little  cautious  in  regard  to  subjecting  the 
•crown  or  bridge  to  any  force  for  a  short  time. 

Dr.  Low's  Method. — The  following  illustrated  account,  de- 
scriptive of  Dr.  J.  E.  Low's  methods  of  procedure  in  the  cases 
under  consideration,  was  especially  prepared  by  him  for  this  work. 
His  definition  of  "  bridge-work "  has  special  application  to  his 
distinctive  method  of  construction.     It  is  as  follows : 

"  Bridge-work  consists  of  supplying  vacancies  between  teeth  or 
roots  with  artificial  teeth,  attached  to  the  adjoining  natural  teeth  or 
roots  by  means  of  bands  or  crowns,  and  held  in  such  a  position  that 
there  is  no  contact  with  or  pressure  on  the  gums  beneath,  and  thus 
no  opportunity  for  secretions  or  other  foreign  matter  to  be  held 
there,  and  thereby  become  offensive. 

"  There  is  really  but  one  kind  of  bridge-work,  and  but  one  way 
to  make  bridge-work  to  insure  success.  There  are  many  ways  of 
making  teeth  without  plates,  but  this  is  not  bridge-work. 

""  For  the  first  illustration,  as  seen  in  Fig.  554,  we  have  a  case 


590 


MECHANICAL   DENTISTRY. 


where  all  the  teeth  have  been  extracted  except  the  two  cuspids  and' 
two  second  molar  roots. 

"  First  proceed  to  prepare  the  roots  by  crowning.  I  use  gold 
crowns  on  the  molar  teeth,  and  what  is  known  as  the  Low  crown 
on  the  cuspids.  The  preparation  of  the  two  cuspids  consists  in 
making  the  crown  ready  for  adjustment,  the  process  of  which  is 
about  the  same  as  for  the  Richmond  crown.  I  always  measure 
the  tooth  to  be  crowned  with  gold  with  a  strip  of  block  tin,  No. 
35  thick  Stub  gage  or  thereabouts.  Place  the  tin  around  the  tooth,, 
and  with  pliers  carefully  measure  the  full  size  of  the  same. 

"  Should  you  be  measuring  a  tooth,  or  part  of  a  tooth,  on  which; 

Fig.  554. 


there  are  projections,  take  the  engine,  and  with  a  stone  grind  off' 
the  same,  making  a  smooth  surface,  so  there  will  be  nothing  to 
interfere  with  the  fitting  of  the  bands  properly.  After  cutting  the 
tin  measures  by  the  marks  made  by  the  pliers,  you  have  the 
measures  ready  to  make  the  gold  bands  by.  Cut  the  bands  and 
bevel  the  edges  and  solder  together,  and  you  are  ready  to  fit. 
After  fitting  all  the  bands  and  finishing  the  crowns  in  the  usual 
way,  place  each  in  position  in  the  mouth,  having  previously  reg- 
ulated the  articulation  of  each  crown  as  desired,  in  the  process  of 
making.  We  now  take  a  deep  articulation  in  wax,  and  impression 
in  plaster-of-Paris ;  remove  before  it  gets  too  hard,  and  place  all 
the  crowns  in  their  positions  in  the  impression;  varnish,   oil,  and'. 


BRIDGE    DENTURES.  59 1 

pour  in  the  usual  way;  separate  the  cast  from  the  impression  and 
place  in  the  articulator.  Then  pour  with  plaster.  After  the 
plaster  has  hardened,  remove  the  wax,  and  we  have  the  articulation 
proper,  and  are  ready  to  select  and  grind  the  teeth,  having-  pre- 
viously selected  the  shade.  My  experience  has  long  ago  taught 
me  that  no  porcelain  tooth  can  stand  the  pressure  for  bridge-work, 
the  strain  on  them  being  twice  as  great  as  with  teeth  on  plates  which 
rest  on  the  gums,  that  give  to  pressure.  In  order  to  prevent  break- 
age of  teeth  and  give  strength,  we  must  supply  the  teeth  with  gold 
cusps.     I  will  here  describe  my  manner  of  doing  so. 

"  For  the  first  step,  use  No.  28  gage  platinum  for  a  covering  of 
the  inside  of  the  tooth,  or  just  where  you  wish  gold  to  flow.  Then 
bend  the  pins  down  to  hold  the  platinum  in  position,  and  with  a 
file  remove  all  overlapping  platinum  to  prevent  breaking  of  the 
tooth  in  heating.  The  tooth  is  made  flat  on  the  crown  surface 
with  the  express  intention  of  restoring  with  a  gold  crown.  This 
crown  need  not  be  very  thick,  but  should  perfectly  resemble  the 
cusps  on  the  natural  tooth,  for  the  purpose  of  mastication.  As 
these  cusps  are  not  on  the  market,  and  every  dentist  making 
bridge-work  cannot  make  it  in  a  way  to  stand  without  putting 
gold  cusps  on  the  grinding  surface  of  the  bicuspids  and  molars, 
I  will  here  describe  how  they  can  be  made  with  very  little  trouble. 
Pick  out  a  natural  tooth  with  cusps  the  exact  shape  you  wish  to 
have  your  gold  cusps  resemble;  mix  up  some  fire  clay  in  a  thick 
paste;  then  press  your  tooth  into  it  a  little  deeper  than  you  wish 
the  cusps.  Having  made  the  proper  impression  remove  the  tooth, 
and  set  the  impression  over  the  gas-stove  to  dry.  After  it  is 
dried  and  reasonably  hot,  lay  your  pieces  of  gold  in  the  impres- 
sion and  with  a  blowpipe  melt  them.  When  melted,  press  with  a 
piece  of  steel  on  the  gold  till  cool.  This  mold  will  do  to  make 
many  from.  If  you  have  not  the  fire  clay,  and  can  get  charcoal 
that  is  burned  from  fine-grained  wood  and  is  soft,  you  can  simply 
press  your  tooth  into  the  charcoal  and  melt  in  the  same  way,  or 
you  can  carve  your  teeth  as  you  desire  in  a  block  of  carbon.  Of 
course,  the  little  steel  die-plates  are  handier,  as  we  can  swage  up  our 
gold  cusps  in  them,  either  solid  or  thin. 

"  Having  described  our  manner  of  making  the  cusps,  we  will 
now  return  to  the  finishing  of  the  tooth.  We  left  off  by  say- 
ing we  covered  the  inside  and  bent  down  the  pins  and  filed  off 


59^ 


MECHANICAL    DENTISTRY. 


Fig.  si 


the  overlapping  platinum.  Now  place  the  cusp  on  the  top  of 
the  tooth,  and  place  in  the  position  desired,  holding  it  there  with 
wax,  and  with  a  spatula  trim  the  wax  the  exact  shape  we  wish 
our  tooth  to  be,  V-shaped,  tapering  from  the  crown  down.  We 
now  incase  in  plaster  and  sand,  which  gives  us  a  box.  When 
hard,  remove  the  wax  and  place  over  the  stove,  and  when  suf- 
ficiently dry  fill  in  with  coin-gold,  using  the  blowpipe  to  melt  it  in 

a  solid  mass,  and  our  tooth  is  ready  to  file  up  and  place 

in  position  on  the  articulator.     Fig.  555  shows  the  tooth 

in  this  condition. 

"  After  our  teeth  are  arranged,  we  hold  the  same  in 

position  with  wax,  remove  from  the  articulator,  incase 
with  plaster  and  sand  or  asbestos  in  the  usual  way.  That  we  may 
have  a  strong  case,  I  always  place  platinum  wire  between  each 
tooth,  and  then  proceed  to  heat  and  solder.  Be  sure  that  all  the 
gold  cusps  are  so  arranged  that  you  can  get  it  all  soldered  together, 
as  this  gives  great  strength.  My  formula  for  solder,  which  will 
be  found  very  easy-flowing,  and  almost  the  exact  color  of  the  gold 
you  are  using,  is  as  follows :  Always  figure  from  the  carat  of  gold 
you  are  working.  Take  one  dwt.  coin-gold,  two  grains  of  copper, 
and  four  of  silver.     We  now  have  our  case  soldered ;  after  filling  as 


Fig.  556. 


desired,  commence  to  finish  with  felt  wheels  and  pumice-stone,  after 
which  use  rouge  on  buff  wheels.  It  is  now  ready  to  be  placed  in 
the  mouth.     In  Fig.  556  we  see  the  case  ready  for  adjustment. 

"  Have  the  assistant  dry  all  the  teeth  or  roots  to  be  operated 
upon  while  you  are  mixing  the  cement.  Be  sure  and  use  a  kind 
which  will  not  harden  very  rapidly,  or  your  cement  will  set  before 
you  get  your  teeth  home.  Use  sufficient  cement  to  fill  all  the 
gold  crowns  perfectly  when  the  case  is  driven  to  place.  Moisten 
the  step-plugs  and  cap  with  cement,  touching  every  portion,  and 


BRIDGE   DENTURES. 


593 


with  an  instrument  place  a  little  cement  in  the  bottom  of  the  cavity. 
We  now  adjust  our  case,  using  a  wooden  plug  for  driving  on  the 
crowns.     Fig.  557  represents  the  case  when  in  position. 

"  It  will  be  seen  by  looking  at  the  previous  cut  (Fig.  556),  that 
the  teeth,  after  having  been  soldered,  are  all  spaced  fully  one-third 
of  the  distance  from  the  place  of  contact  with  the  gums  and  the 

Fig.  557. 


grinding  surface  of  the  teeth,  so  that  secretions  could  not  possibly 
lodge  there." 

Dr.  Melotte's  Method.— Dr.  G.  W.  Melotte,  of  Ithaca,  N.  Y., 
contributed  to  the  Dental  Cosmos  an  account  of  his  method  of 
bridging  in  a  given  case,  the  manipulative  details  of  which  are  here 
reproduced : 

"  Fig.  558  illustrates  a  case  for  the  supply  of  a  lateral  and  a 
bicuspid.     In  this  instance  the  cuspid   should  be  cut  off,  and  the 

Fig.  558. 


root  collared  and  capped  in  combination  with  a  pin  entering  the 
enlarged  pulp  canal;  but,  as  there  may  be  grounds  for  objecting  to 
cutting  off  sound  teeth,  I  obviate  the  necessity  by  cutting  a  shoulder 
on  the  lingual  portion  of  the  cuspid,  and  suitably  shaping  its  sides 
to  permit  a  close  fitting  of  the  collar  just  under  the  free  margin  of 
the  gum.  A  narrow  strip  of  pure  pattern  tin,  bent  tight  around 
the  tooth  neck,  and  cut  through  with  a  knife  at  the  lap  on  the 
labial  surface,  will  serve  as  a  measure  for  the  length  of  a  strip 
38 


594  MECHANICAL   DENTISTRY. 

of  22-carat  gold  plate,  No.  29,  thick,  and  as  wide  as  the  length 
of  the  distal  side  of  the  cuspid.  The  ends  of  the  gold  are 
then  squared,  and  with  round-nosed  pliers  brought  evenly  together, 
to  be  held  in  flush  contact  with  suitable  pliers.  The  soldered 
collar,  with  its  joint  side  inward,  is  then  adjusted  on  the  tooth  as 
accurately  as  possible,  giving  slight  blows  with  a  mallet  until  the 
collar  touches  the  gum,  when  it  should  be  marked  to  indicate  the 
necessary  trimming  to  conform  it  to  the  gum  contour.  After  it 
has  been  thus  trimmed,  the  edges  beveled,  the  labial  part  swelled 
with  contouring  pliers,  and  the  lingual  part  cut  down  to  about  J^ 
of  an  inch  in  width,  the  collar  is  again  driven  on,  and  will  appear 
as  seen  in  Fig.  558.  A  stump  corundum  wheel  is  then  used  to 
grind  a  shoulder  on  the  lingual  surface  of  the  tooth,  grinding  also 
the  edges  of  the  collar  flush  with  the  shoulder.  The  collar  is 
again  removed,  and  a  piece  of  thin  platinum  plate,  about  No.  32, 

Fig.  559.      Fig.  560.         Fig.  561. 


sufficient  to  cover  the  lingual  surface  of  the  tooth,  is  caught  on  the 
lingual  edge  of  the  collar  by  the  least  bit  of  solder,  and  all  put  in 
place  on  the  cuspid  (see  Fig.  559).  The  platinum  should  now  be 
burnished  on  to  the  shoulder,  and  over  the  tooth  and  collar  to  the 
extent  shown  by  the  lines  in  Fig.  559.  After  trimming  to  those 
lines,  and  carefully  replacing  and  burnishing  to  the  tooth,  the  collar 
and  half  cap  are  removed,  filled  with  wet  plaster  and  sand,  and  the 
platinum  soldered  to  the  gold.  It  is  then  placed  on  the  tooth,  bur- 
nished into  all  the  inequalities  of  the  tooth,  very  carefully  removed, 
invested,  and  enough  solder  flowed  over  the  platinum  to  cover  and 
give  it  strength.  Fig.  560  shows  it  complete  on  the  cuspid.  I  have 
often  made  such  collars  in  less  than  an  hour,  and  in  any  case  time 
must  be  made  subservient  to  exactness  of  fit  and  adaptation  to  the 
end  in  view. 

"  In  the  preparation  for  fitting  a  collar  on  the  first  molar   (Fig. 
558)    I    should   have   wedged   or  otherwise   separated   it   from   the 


BRIDGE   DENTURES.  595 

second  molar,  so  that  a  piece  of  sheet-brass  might  be  put  in  place, 
as  shown  in  Fig.  561,  and  an  impression  taken  in  plaster,  which,  if 
allowed  to  get  hard,  would  bring  away  the  metal.  If  not,  it  could 
be  replaced  in  the  plaster.  Melted  fusible  metal,  when  near  the 
cooling-point,  is  then  poured  into  the  impression,  and  when  cold 
will  allow  the  safe  removal  of  both  the  plaster  and  the  metal  strip. 
On  this  metal  model  a  collar  can  be  formed  that  will  accurately- 
fit  the  molar,  as  seen  in  Fig.  558.  If  the  molar  has  no  antagonist, 
a  cap  may  at  once  be  struck  up  on  the  model;  but  if  there  be  an 
antagonist,  the  cusps  of  the  natural  molar  should  be  removed  by 
grinding  at  points  where  the  occluded  tooth  will  admit  of  sufficient 
thickness  of  the  gold  cap.  An  exact  copy  of  the  ground  cusps 
can  then  be  made  in  less  than  five  minutes  by  the  use  of  moldine 
with  its  accessories,  see  page  138,  and  the  process  is  as  follows: 
Make  the  tooth  perfectly  dry.  Put  the  collar  on  it.  Nearly  fill 
the  cup  with  moldine,  and  coat  it  with  soapstone  powder.  Press 
the  compound  on  the  tooth  and  collar  firmly  to  about  one-fourth  the 
depth  of  the  tooth.  Carefully  remove  the  cup ;  trim  off  any  over- 
hanging material,  and  place  the  rubber  ring  over  the  cup  to  about 
one-half  the  depth  of  the  ring.  Melt  the  fusible  metal  and  pour  it 
as  cool  as  it  will  run  from  the  iron  ladle.  As  soon  as  the  metal  is 
hard,  remove  it  with  the  ring,  taking  care  not  to  impair  the  im- 
pression, which  can  be  used  again  if  the  die  is  found  imperfect  or 
gets  injured  in  use.  Place  the  die  and  ring  in  cold  water,  to  remain 
until  quite  cooled.  While  the  die  is  wet  and  held  over  a  basin  of 
water,  pour  into  the  ring  fusible  metal  which  has  been  stirred  until 
it  begins  to  granulate,  and  quickly  immerse  all  in  the  water.  The 
die  and  counter-die  should  separate  readily  by  tapping  them  with  a 
hammer,  but  if  they  stick,  others  can  be  quickly  made  from  the 
same  impression,  by  the  same  method,  using  more  care.  With  this 
die  and  its  counter-die,  a  piece  of  No.  29  or  30  gold  plate  is  swaged 
to  fit  perfectly  the  cusps  and  collar,  which,  when  removed,  can  be 
held  to  its  place  on  the  cap  by  the  soldering  clamp,  using  spring 
pressure  enough  merely  to  hold  them  together  for  careful  soldering 
with  the  pointed  flame  so  as  not  to  unsolder  the  collar.  The  seam- 
less collars  are  excellent  when  care  is  used  in  selecting  the  proper 
size,  as  directed  on  the  diagram. 

"  The  caps  being  in  place  on  the  cuspid  and  molar,  an  impression 
is  taken  with  plaster,  the  caps  accurately  set  in  the  impression,  and 


596  MECHANICAL   DENTISTRY. 

hard  wax  melted  with  a  hot  spatula  around  the  edges  of  the  caps. 
The  impression  is  then  thoroughly  coated  with  sandarac  varnish, 
after  which  it  is  dipped  for  a  moment  in  water  and  filled  with  a  wet 
mixture  of  one  part  marble-dust  with  two  parts  of  plaster,  using 
great  care  to  perfectly  fill  the  caps  and  molds  of  the  teeth.  Wait 
until  this  mixture  has  become  quite  hard,  remove  the  cup,  and  with 
a  suitable  knife  clip  off  the  plaster  without  marring  the  cast ;  secure 
a  good  articulating  impression,  and  transfer  it  to  the  cast  to  obtain 
an  exact  reproduction  of  the  relative  occlusions  of  all  the  teeth 
involved.  With  such  an  articulation  in  hand,  and  with  the  means 
already  described  for  swaging  gold  or  platinum  plate  to  fit  the 
cusps  and  articulating  surfaces  of  either  the  natural  or  artificial 
teeth,  it  should  be  within  the  capacity  of  any  competent  dentist  to 
complete  a  suitable  bridge,  although  there  are  practical  points  that 
can  only  be  imparted  by  clinical  instruction  and  actual  demonstra- 
tion in  the  mouth.     Such  a  bridge  is  shown  in  position  in  Fig.  562." 

Fig.  562. 


The  Mandrel  System.— The  following  description  of  "  A  Sys- 
tem of  Crown-  and  Bridge-work  "  is  given  by  the  experts  of  the 
S.  S.  White  Manufacturing  Co.,  who  have  designated  it  as  "  The 
Mandrel  System  " : 

"  An  examination  of  a  large  number  of  human  teeth  shows  that, 
no  matter  how  great  differences  may  exist  in  the  apparent  shapes 
of  the  crowns  of  individual  teeth  of  a  given  class,  there  is  a  remark- 
able uniformity  in  the  configuration  of  their  necks.  That  is,  the 
necks  of  upper  cuspids,  for  instance,  were  found  to  have  a  fixed 
type,  from  which  the  variations  were  very  slight  as  to  shape,  though 
there  appeared  to  be  no  exact  standard  of  size.  So  of  the  other 
classes,  with  the  single  exception  of  the  superior  molars,  in  which 
two  distinct  forms  were  found,  the  first  being  those  in  which 
the  buccal  roots  were  wider  than  the  palatal ;  the  second,  those  in 
which  the  reverse  condition  was  found,  the  single  palatal  root  being 
wider  at  its  junction   with  the  crown  than  the  two  buccal   roots. 


Fig.  563. 


=q 


No.  1. 


No.  2.  No.  8. 

Mandrels   for   shaping 


No,  4.  Ho.  6.  No.  fl. 

seamless  tooth-root  collars. 


a, 
3 
02 


'a, 

3 

o 
M 
t3 


No.  7. 


597 


593 


MECHANICAL    DENTISTRY, 


The  occurrence  of  roots  of  the  second  class  being  rather  excep- 
tional, the  first  class  was  accepted  as  the  type. 

"  The  configuration  of  the  necks  of  all  the  teeth  having  been 
determined,  a  set  of  mandrels  for  shaping  collars  to  fit  them  was 
devised.  The  set  (Fig.  563)  consists  of  seven  mandrels,  six  of  which 
are  double  end.     Their  shapes  are  modeled  upon  the  general  typal 


Fig.  564. 


forms  of  the  necks  of  the  teeth  which  they  represent,  and  they  are 
made  tapering  to  provide  for  all  required  variations  in  size.  The 
illustrations  are  about  two-thirds  actual  size,  the  longest  instruments 
being  nine  inches  in  length.  The  cross-sections  show  the  shapes  and 
proportionate  sizes  at  the  greatest  and  least  diameters.  The  long 
taper  permits  the  most  minutely  accurate  adjustment  of  the  collars. 


BRIDGE   DENTURES. 


599 


"  No.  i  is  a  double-end  mandrel,  for  superior  molars,  right  and 
left ;  No.  2  is  a  single  mandrel,  for  superior  bicuspids,  right  and 
left ;  No.  3  is  a  double-end,  for  superior  cuspids,  right  and  left ;  No. 
4,  double-end,  for  superior  centrals,  right  and  left;  No.  5,  double- 
end,  for  inferior  molars,  right  and  left;  No.  6,  double-end,  for  the 
inferior  centrals,  laterals,  cuspids,  and  first  bicuspids,  right  and  left; 
No.  7,  double-end,  one  end  for  the  superior  lateral  incisors,  the 
other  for  those  bicuspids  in  which  a  bifurcation  of  the  roots,  or  a 
tendency  in  that  direction,  extends  across  the  neck  to  the  crown  in 
the  form  of  a  depression  on  one  or  both  approximal  surfaces.  The 
foregoing  scheme  comprehends  all  the  teeth  of  the  permanent  set 
except  the  second  inferior  bicuspids.  The  necks  of  these  approxi- 
mate those  of  the  superior  central  incisors  so  closely  in  shape  that 
it  was  deemed  inexpedient  to  make  a  separate  mandrel,  as  the  No. 
4  mandrel  will  serve  for  both. 

"  The  collars  or  bands  are  made  seamless,  of  No.  30  (American 
gage)  gold  plate,  22  carats  fine.  Fifteen  sizes,  each  of  three  widths 
(iV>  To'  an^  to"  °f  an  mch)  are  made  (Fig.  565),  which  it  is  be- 
lieved will  cover  all  requirements.  These  collars,  although  devised 
as  a  part  of  the  system,  can  be  used  in  all  methods  of  crown-  and 
bridge-work  which  require  bands,  and  possess  many  advantages 
over  any  others.  They  are  really  labor-saving  devices,  as  their  use 
saves  the  time  and' trouble  of  making,  and  there  is  no  danger  of 
their  coming  unsoldered  when  the  pins  or  the  backing  of  the  crown 
are  being  soldered;  and  there  are  no  hard  spots  to  give  trouble  in 
burnishing,  as,  for  instance,  close  to  the  root,  after  the  collar  has 
been  shaped  and  placed  in  position,  the  whole  surface  being  uni- 
formly soft. 

"  The  seamless  collars  are  also  especially  adapted  to  removable 
or  detachable  bridge-work.  They  are  so  constructed  that  Nos.  1, 
16,  and  31  exactly  fit  into  or  telescope  with  Nos.  2,  17,  and  32,  and 
so  on  through  the  entire  set,  each  collar  fits  into  the  series  next 
higher ;  so  that  a  root  may  be  banded  with  one  size  and  the  size 
next  larger  used  to  form  the  tube  for  the  telescoping  crown.  When 
desirable,  the  '  seamless '  collar  can  be  strengthened,  after  it  has 
been  adapted  to  the  conformation  of  the  crown  so  as  to  slide  freely 
over  it,  by  investing  and  flowing  solder  over  the  outer  surface;  or, 
still  better,  by  adapting  the  next  larger  size  of  collar  to  exactly  fit 
around  the  first,  and  then  investing  the  two  and   soldering  them 


( 


o 

o 
o 

o 
o 
o 
o 


Fig.  565. 


ft 


S> 


X 


» 


e 


88 


«(D 
-(D 


?« 


VZ. 


§D 

2D 
2D 
BD 

20 


O 


J 


M    li. / 

S  O 


BRIDGE    DENTURES. 


60 1 


together.     The  advantages  of  these  collars  for  this  kind  of  work,  and 
also  for  the  construction  of  cap  crowns,  are  obvious. 

"  The  other  appliances  specially  devised  for  this  system  are,  a  re- 
ducing plate  or  contractor,  a  pair  of  collar  pliers,  and  a  hammer. 

Fig.  566. 


"  The  contractor  (Fig.  564)  contains  holes  which  are  comple- 
mentary in  shape  to  the  mandrels.  The  mandrels  being  applied  to 
the  inner  circumferences  of  the  collars,  while  the  contractor  must 
admit  the  collars  themselves,  the  short  taper  of  the  holes  in  the 
contractor  necessarilv  covers  a  somewhat  greater  range  of  size  than 


602 


MECHANICAL    DENTISTRY. 


Fig.  567. 


is  shown  in  the  mandrels.  With  this  appliance  collars  can  be  evenly 
and  accurately  reduced  in  size  at  the  edges,  without  burring  or 
buckling.     The  illustration  is  actual  size. 

"  The  collar  pliers  (Fig.  566)  are  for  contouring 
the  collars  to  shape,  one  beak  being  made  convex 
and  the  other  concave  to  correspond.  With  this 
appliance  the  slightest  changes  required  in  the 
contour  of  the  collars  are  easily  made.  About 
*/2  of  an  inch  from  the  extremity  of  the  concave 
beak  a  small  bar  of  flat  steel  is  attached  to  it  by 
means  of  a  screw.  The  free  end  of  the  bar  has 
a  minute  projection  upon  one  face,  the  other  be- 
ing reinforced  to  fit  into  the  concavity  of  the  beak. 
In  the  center  of  the  face  of  the  convex  beak  is  a 
depression,  into  which  the  projection  on  the  steel 
bar  strikes,  making  a  very  efficient  punch  for 
forming  guards  or  stops  to  prevent  the  collars 
from  being  forced  too  far  under  the  gum.  The 
depression  in  the  convex  beak  being  slightly 
larger  than  the  projection  or  punch,  the  metal  is 
not  cut  through,  but  merely  raised  on  the  side 
opposite  to  the  punch.  The  punch  attachment 
being  pivoted  can  be  swung  to  one  side  when  not 
in  use. 

"  The  mallet  or  hammer,  with  steel  face  and 
horn  peen,  is  shown  in  Fig.  567. 

"  One  of  the  appliances  required  is  a  lead  anvil, 
which,  being  only  a  piece  of  soft  lead,  say  two  by 
three  inches,  and  an  inch  thick,  is  not  illustrated. 
The  counter-die  of  an  ordinary  case  will  answer 
very  well. 

"  To  illustrate  the  uses  of  these  appliances,  take 
a  case  in  which  the  two  inferior  bicuspids  of  the 
left  side  are  missing,  and  the  crowns  of  the  cuspid 
and  first  molar  so  badly  decayed  that  the  prob- 
abilities arc  that  they  will   soon   fall   victims  to 
the   forceps.     The   old-time   way   would   have   been   to   extract   the 
molar  and  cuspid,   and   make   a  partial   plate.     Examination,   how- 
ever,  shows   that  the   roots  of  these  two   teeth   are   in   good   con- 


BRIDGE    DENTURES. 


603 


dition,  affording  an  excellent  opportunity  for  the  construction  of  a 
piece  of  bridge-work. 

"  With  a  corundum  stone,  cut  off  the  remaining  portions  of  the 
crowns  level  with  the  gum  margins.  Prepare  the  roots  in  any  of 
the  well-known  ways,  thoroughly  cleansing  the  apical  portions 
and  filling  them  with  whatever  material  is  desired,  being  careful 
only  that  the  work  is  well  done.  For  the  better  retention  of  the 
filling  material  to  be  placed  in  the  pulp  chamber,  retaining  grooves 
can  be  made  or  retaining  posts  inserted.  Take  a  piece  of  binding 
wire  (No.  26,  American  gage),  say  2^  inches  long,  pass  it  around 
the  neck   of  the  molar  stump,   cross   the   free  ends,    and,   holding 


Fig.  s< 


Fig.  569. 


Fig.  570. 


the  wire  in  place  with  one  finger,  twist  the  ends  with  a  pair  of 
flat-nosed  pliers  until  the  wire  clasps  the  tooth  closely  at  every 
point  (Fig.  568).  When  there  are  any  irregularities  in  the  con- 
tour of  the  tooth,  it  is  necessary  to  press  the  wire  into  them 
with  an  approximal  burnisher.  It  is  obvious  that  the  ring  thus 
formed  will  show  the  exact  size  and  shape  of  the  neck  of  the 
tooth.  Remove  the  ring  carefully,  lay  it  on  the  lead  anvil,  put  over 
it  a  piece  of  flat  metal,  and  with  a  smart  blow  from  a  hammer 
drive  the  wire  into  the  lead  (Fig.  569).  Upon  removing  the  wire 
an  exact  impression  of  the  ring  will  be  left  in  the  lead  anvil,  as 
shown  in  Fig.  570.  (This  part  of  the  work,  as  indeed  all  others, 
should  be  done  carefullv  as  described.     The  wire  ring  mav  be  driven 


604  MECHANICAL   DENTISTRY. 

into  the  lead  by  a  direct  blow  of  the  hammer  face,  but  the  blow- 
might  not  strike  equally,  and  the  interposition  of  the  flat  metal 
held  level  insures  an  even  impression.  A  piece  of  an  old  file  is 
best,  as  the  file-cuts  keep  the  wire  from  slipping.) 

"  Next,  cut  the  wire  ring  at  the  lap,  straighten  out  the  wire,  and 
select  a  suitable  collar  by  comparing  the  length  of  the  wire  with 
the  straight  lines  in  the  diagram,  which  show  the  inside  diameters 
of  the  various  sizes.  Should  none  of  these  correspond  exactly, 
take  preferably  the  next  size  smaller.  It  will  be  remembered  that 
the  collars  are  No.  30  in  thickness,  while  the  wire  with  which  the 
conformation  is  secured  is  No.  26.  This  difference  permits  the 
collar,  when  contoured  to  shape,  to  enter  the  lead  impression 
readily,  a  decided  advantage  in  fitting.  Having  selected  the  collar, 
fit  it  to  mandrel  No.  5,  with  the  peen  of  the  hammer,  holding  it 
upon  the  lead  anvil,  and  using  a  slight  pushing  force  to  help  in 
stretching  and  forming  it  (Fig.  569).  Having  driven  the  collar  to 
form,  remove  it  from  the  mandrel  and  try  in  the  lead  impression. 
If  it  does  not  fit  exactly  return  it  to  the  mandrel  and  stretch  it  a 
little,  when  it  will  usually  fit  perfectly,  as  the  mandrels  have  been 
designed  carefully  to  the  average  shapes  which  obtain  in  the 
great  majority  of  tooth  necks.  In  the  exceptional  cases  where 
the  collar  does  not  fit,  it  can  readily  be  contoured  to  the  exact 
shape  with  a  pair  of  flat-nosed  pliers.  Of  course,  if  it  fits  the  im- 
pression in  the  lead,  it  will  fit  the  neck  of  the  tooth,  always  pro- 
vided the  measurement  and  the  impression  have  been  carefully 
made. 

"  If  the  collar  or  band  has  been  accidentally  stretched  too  much, 
or  if,  for  any  reason,  when  brought  to  shape,  it  is  too  large,  its- 
root  end  can  easily  be  reduced  to  the  proper  size  by  the  use  of  the 
contractor.  Place  the  edge  of  the  collar  which  is  to  fit  in  the  root 
in  the  proper  hole;  hold  it  level  with  a  piece  of  file  as  in  taking 
the  lead  impression  of  the  ring,  and  tapping  lightly  on  the  file 
drive  the  collar  into  the  plate  (Fig.  564)  until  the  proper  reduction 
is  made.  The  collar  is  next  '  festooned '  to  correspond  to  the 
shape  of  the  maxillary  ridge.  Lay  it,  gum  edge  up,  on  the  lead 
anvil,  and  with  the  piece  of  flat  file  and  the  hammer  drive  it  into' 
the  lead.  A  few  cuts  with  a  fine  half-round  file  across  the  approxi- 
mal  diameter  will  conform  the  edges  to  the  surface  of  the  ridge 
(Fig.  571).     Then  place  the  collar  in  position,  and,  having  ascer- 


BRIDGE   DENTURES. 


605 


tained  just  how  far  it  should  go  down  on  the  root,  remove  it,  and 
with  the  small  spring  punch  in  the  collar  pliers  (Fig.  566)  form 
projections  on  the  inside  of  the  band  at  the  proper  points  to  serve 
as  stops,  which,  resting  on  the  top  of  the  root,  will  prevent  the 
collar  from  being  forced  further  down  upon  it  than  is  desirable 
(Fig.  572). 
"  A   collar   for   the   cuspid   is   then   fitted   in   the    same   manner, 

Fig.  571.  Fig.  572. 


.  Hi 


using  mandrel  No.  6  for  shaping,  after  which  the  case  is  ready  for 
the  building  of  the  bridge. 

"  Place  both  collars  in  position  and  take  an  impression  of  the 
parts,  including  the  interiors  of  the  excavated  pulp  chambers,  from 
which  make  a  cast  in  the  usual  way.  Bend  a  short  piece  of  half- 
round  gold  or  platinum  wire  into  the  form  of  a  horseshoe,  the 
two    extremities   of   which   shall   fit   into   the   roots   of   the   molar. 


Fig.  573. 


Then  take  a  longer  piece  of  the  same  wire,  somewhat  more  than 
enough  to  extend  from  the  toe  of  the  horseshoe  when  in  position 
to  the  cuspid  root;  bend  one  end  of  it  at  a  right  angle,  or  nearly 
so,  to  fit  the  root  of  the  cuspid,  and,  cutting  off  any  excess  of 
length,  solder  the  other  end  to  the  toe  of  the  horseshoe.  The 
bar  extending  between  the  two  roots  is  the  truss  of  the  bridge. 
Next,   place  the   appliance  on   the   cast    (Fig.   573),   holding  it   in 


6o6 


MECHANICAL   DENTISTRY, 


position  with  wax,  and  select  the  teeth  to  take  the  place  of  the 
missing  bicuspids  and  molar.  The  best  form  for  this  purpose  is 
a  tooth  having  holes  extending  through  it  vertically  from  the 
neck  to  the  grinding  surface,  similar  to  the  well-known  Bonwill 
crown. 

"  The  crowns  used  should  be  large  enough  to  fill  the  space  rather 
tightly,  even  if  their  sides  have  to  be  flattened  to  let  them  in.  If 
the  teeth  do  not  fill  the  space  perfectly,  a  small  portion  of  plastic 
filling  material  crowded  between  them,  as  mortar  between  the 
granite  blocks  in  the  arch  of  a  railway  bridge,  will  greatly  increase 
the  strength  of  the  work. 

"  After  the  teeth  are  ground  to  fit,  and  the  proper  length  for 
occlusion  ascertained,  the  truss  is  covered  with  a  film  of  wax,  upon 
which  the  crowns  are  again  pressed  to  their  positions.     Upon  the 

Fig.  574. 


removal  of  the  crowns  the  impression  of  the  holes  running  through 
them  will  be  found  in  the  wax.  At  these  points  drill  holes  through 
the  bar  with  a  small  twist  drill  run  by  the  dental  engine,  and  into 
these  fit  and  solder  the  pins  for  the  support  of  the  crowns,  as  shown 
in  Fig.  574. 

"  The  bridge  is  now  ready  to  be  attached  permanently.  Set  the 
crowns  in  position  upon  their  supporting  pins,  to  secure  the  proper 
alignment.  (If  the  operation  were  upon  the  upper  jaw  they  would 
have  to  be  held  with  wax.)  Put  into  the  canals  of  the  supporting 
roots  (the  cuspid  and  first  molar)  a  sufficient  quantity  of  some 
quick  setting  plastic,  as  oxyphosphate,  to  about  half  fill  the  pulp 
chamber,  but  not  enough  to  prevent  the  supports  of  the  truss 
from  being  forced  home.  Force  the  bridge  supports  to  place,  and 
after  allowing  the  filling  material  to  become  set  remove  the  crowns. 


BRIDGE    DENTURES. 


607 


Fill  the  remainder  of  the  pulp  chamber  and  the  whole  of  the 
collar  with  gold,  amalgam,  gutta-percha,  oxyphosphate,  or  other 
suitable  plastic  (Fig.  574).  Set  the  crowns  permanently,  the 
molar  and  cuspid  first,  as  this  affords  greater  facility  for  the 
trimming  off  of  any  excess  of  the  filling  material  used  in  the  at- 
tachment. For  attachment  of  the  crowns  gutta-percha  is  probably 
the  best  material,  as  crowns  set  with  it  are  readily  removed  for  the 
correction  of  any  inaccuracies  of  occlusion  or  alignment  by  grasp- 
ing them  between  the  beaks,  previously  warmed,  of  a  pair  of  uni- 
versal lower  molar  forceps.  The  heat  warms  the  gutta-percha  and 
releases  the  tooth,  which  can  then  be  reset  properly.  In  attaching 
crowns  with  gutta-percha,  the  holes  in  the  crowns  are  first  filled 
with  the  material,  after  which  the  crown  is  wanned  and  forced  to 
place.     Any  of  the  other  plastics  ordinarily  used  can  be  employed, 


at  the  discretion  of  the  operator.  Fig.  575  shows  the  case  com- 
pleted. 

"  In  securing  the  occlusion  of  a  piece  of  bridge-work  it  is  well 
to  make  the  artificial  teeth  a  little  short,  so  that  the  natural  teeth 
on  both  sides  will  meet  the  first  shock  of  mastication.  Nature 
will  correct  the  occlusion  in  time  by  slightly  elongating  the  roots 
supporting  the  bridge.  If  the  artificial  crowns  are  permitted  to 
strike  the  natural  teeth  from  the  first,  the  undue  strain  upon  the 
two  supporting  roots  will  cause  soreness  and,  perhaps,  more  serious 
consequences. 

"  When  a  sound  tooth  is  to  be  used  as  one  of  the  supports  of  the 
bridge,  a  modification  of  the  method  just  described  is  necessary. 
Take  a  case  where  it  is  desired  to  bridge  the  space  caused  by  the 
loss  of  the  right  inferior  bicuspids  and  first  molar.     The  crown  of 


6o8 


MECHANICAL    DENTISTRY. 


the  right  cuspid  is  nearly  gone,  but  the  root  is  sound  and  capable 
of  supporting  one  end  of  the  bridge.  The  other  end  will  be  attached 
to  the  second  molar,  which  is  a  sound  tooth.  Prepare  and  band 
the  cuspid  root  as  before,  dress  off  the  second  molar  crown  until  it 
is  slightly  smaller  than  the  neck,  so  as  to  permit  a  cap  to  be  tele- 
scoped over  it,  and  take  the  measure  of  the  crown  with  the  binding 
wire.  Select  a  suitable  seamless  collar  of  sufficient  width  to  extend 
from  the  neck  to  a  little  beyond  the  grinding  surface  and  drive  it  up 
on  the  pro.per  mandrel  to  get  the  general  shape,  but  not  the  full  size 
required  to  fit  the  tooth,  leaving  it  so  that  the  edge  having  the 
larger  circumference  will  just  pass  over  the  end  of  the  crown; 
place  the  collar  on  the  tooth  and  with  a  block  of  wood  and  the 
mallet  tap  it  to  place  just  beyond  the  free  margin  of  the  gum. 
This  method  will  make  a  close  fit,  as  the  collar  will  readily  stretch 

Fig.  576. 


all  that  is  necessary.  With  a  sharp-pointed  instrument  mark  the 
length  of  the  crown,  remove  the  collar,  and  cut  it  to  the  proper 
width  as  indicated.  Then  in  a  piece  of  gold  plate  of  the  thickness 
used  for  caps  form  four  little  depressions  of  the  general  character 
of  an  impression  of  the  molar  cusps.  An  easy  way  to  do  this  is 
to  lay  the  plate  on  the  lead  anvil;  then  with  the  ball  on  the  end  of 
an  ordinary  socket  handle  and  the  hammer  the  depressions  are 
made  in  a  moment.  Set  the  collar  on  the  plate,  borax  it,  charge 
with  solder,  and  heat  until  the  solder  flows.  Cut  off  the  surplus 
plate,  and  a  perfect  cap  for  the  molar  is  made.  Place  it  on  the 
tooth  and  take  an  impression,  and  thereafter  proceed  as  before 
directed  to  make  the  truss  of  the  bridge  and  mount  the  teeth, 
except  that  in  this  case  the  posterior  end  of  the  truss  is  to  be  sol- 
dered to  the  molar  cap.      For  the  final   attachment  place   a   little 


BRIDGE   DENTURES. 


609 


oxyphosphate  or  other  plastic  filling  material  in  the  cap  to  secure 
it  firmly  in  position." 

The  Hollingsworth  System. — This  system  supplies,  in  the  first 
place,  a  variety  of  forms  for  the  various  teeth  great  enough  to  cover 
almost  any  case,  and  for  the  rare  cases  which  cannot  be  suited  direct 
it  affords  a  ready  means  of  making  the  exact  form  required.  They 
are  made  of  metal,  and  are  used  as  patterns  from  which  to  make 
dies  or  molds,  as  may  be  required,  for  the  swaging  of  gold  cusps 
or  crowns.  There  is,  therefore,  no  wear  upon  them,  and  they  re- 
tain their  shapes  and  sizes  unaltered. 

The  outfit  for  working  these  forms  consists  of  a  molding-plate, 
three  rubber  rings,  a  sheet  of  asbestos,  10  X  7  inches,  and  a  carbon 
stick  for  use  in  casting. 


Fig.  577. 


Fig.  579. 


Fig.  578. 


This  system  permits  cusps  to  be  made  either  hollow  or  solid. 
Scrap  gold  can  be  used  for  casting  solid  cusps,  and  porcelain  fac- 
ings can  be  quickly  inserted  in  crowns  without  investing;  but  per- 
haps its  most  important  advantage  is  the  exactness  with  which  the 
fit  and  articulation  of  bridges  are  obtained  and  maintained. 

The  features  which  Dr.  Hollingsworth  claims  for  his  methods 
are  illustrated  in  the  following  directions : 

After  making  a  band  to  fit  the  root  in  the  ordinary  way,  place  it 
in  the  mouth  (see  Fig.  577),  and  cut  off  on  a  line  where  the  adjoin- 
ing teeth  begin  to  turn  to  form  the  cusp  (see  c,  Fig.  577).  Place  a 
small  piece  of  wax  inside  the  band  to  assist  in  holding  the  cusp 
button,  which  should  be  selected  to  fit  the  circumference  of  the 
band,  to  articulate  properly,  and  to  correspond  in  shape  with  the 
other  teeth  (see  b,  Fig.  577).  Remove  the  button,  and  place  it  on 
39 


Fig.  580. 


am 


m 


' r "■'. ". ."""■- '■'^::..^-7:~:^7r:-'.'.^vl ~:  4Z^4-~:r  4 :-:  ^wy^S^ 


BRIDGE   DENTURES. 


611 


the  molding-plate  with  the  grinding  surface  up  (see  Fig.  578). 
Place  the  small  rubber  ring  d  around  it,  with  the  button  as  near 
the  center  as  possible,  and  pour  in  a  sufficient  quantity  of  Melotte's 
metal  to  nearly  fill  the  ring  (Fig.  579).  Start  to  pour  the  metal 
directly  on  top  of  the  cusp,  otherwise  the  flow  of  metal  may  force 
the  cusp  to  one  side  and  make  an  imperfect  die.  As  soon  as  the 
metal  sets,  chill  the  surface  by  dipping  in  water  for  a  moment,  and 
then  remove  the  rubber  ring.  When  the  heat  begins  to  return  to 
the  surface,  a  quick  rap  of  the  die  on  the  bench  will  cause  the  cusp 
button  to  drop  out  and  leave  the  mold  ready  to  form  the  gold  cusp. 
Xow  take  a  small  piece  of  lead,  and  with  a  few  taps  of  the  ham- 


Fig.    581. 


Fig.    58; 


Fig.    583. 


Fig.  584. 


mer  drive  it  into  the  Melotte  metal  die    (Fig.   581)    to   form   the 
counter-die  (Fig.  581,  d). 

Anneal  the  gold  plate,  and  start  the  swaging  process  by  coaxing 
the  plate  into  the  die  by  hand  pressure  (Fig.  582),  using  a  piece  of 
wood,  which  makes  a  depression  for  the  lead  counter-die  to  rest  in. 
Then  place  the  counter-die  on  the  gold  plate  (Fig.  583),  and  drive 
to  a  partial  fit.  Remove  the  partially  formed  cusp,  pickle  it  to  re- 
move traces  of  lead,  and  again  anneal  it.  Place  the  counter-die  on 
the  die  without  the  gold  plate  and  drive  it  in  with  a  smart  blow  ; 
this  will  resharpen  all  the  lines  of  the  counter-die.  Next  replace 
the  partly  formed  gold  cusp  in  the  die,  and  again  drive  the  counter- 
die  into  it  for  a  perfect  fit.  Again  pickle  the  cusp  and  proceed 
to  cut  the  surplus  metal  from  it  with  shears  (Fig.  584),  filing  up  the 


6l2 


MECHANICAL    DENTISTRY, 


edges  when  necessary,  and  rub  down  the  under  surface  on  a  smooth 
file  until  it  fits  the  band  made  for  it  (Fig.  577).  Wire  the  cusp  and 
crown  together  (Fig.  585),  place  flux  and  solder  in  the  cap,  and 
hold  over  a  lamp  until  soldered.     Then  finish  in  the  usual  way. 

If  the  forms  of  cusp  buttons  do  not  afford  one  which  articulates 
perfectly,  the  difficulty  is  easily  remedied  by  taking  the  button 
which  most  nearly  answers,  and  building  up  the  cusps  with  Mel- 
otte's  moldine  (Fig.  586).  If  necessary  to  make  an  absolutely  per- 
fect articulation,  and  the  forms  as  supplied  do  not  permit  of  it, 
select  a  cusp  that  will  otherwise  suit  the  case,  set  it  on  the  band 
on  the  crown,  cover  the  face  of  the  cusp  with  moldine,  coating  the 


Fig.   5S5. 


Fig. 


Fig.  587. 


L_ 


3 


surface    with    collodion    to    prevent    the    saliva    from 
crumbling  it,  and  direct  the  patient  to  bite  upon  it,  or, 
if  a  perfect  plaster  model  has  been  made,  articulate  the 
opposing  teeth    with   the   cusp   placed   on   the   band, 
omitting    the    coating    with    collodion.     Remove    the 
cusp  with  the  moldine,  trim  off  the  surplus,  and  pro- 
ceed to  cast  as  shown  in  Fig.  579.     If  a  band  is  acci- 
dentally cut  too  short,  it  can  still  be  utilized.     Place 
moldine   upon   the   molding-plate,   put   the   cusp   but- 
ton upon  it,  press  down  and  adjust  to  make  up  the  deficiency  of  the 
band,  cutting  away  the  surplus  moldine.    This  will,  of  course,  throw 
the  soldering  line  a  little  further  up  on  the  crown  (Fig.  587). 

Solid  Cusps. — Scrap  gold  can  be  utilized  for  making  a  solid 
gold  cusp  by  casting  in  asbestos  by  the  following  method : 

After  selecting  the  desired  cusp  button,  instead  of  making  a  mold 
in  Melotte's  metal,  as  before  described,  take  a  piece  of  asbestos 
board  about  one  inch  square  and  34  °f  an  mcn  thick,  moisten  it, 
and  with  a  hammer  drive  the  cusp  button  into  it,  flush  with  the  sur- 
face of  the  button.     (See  Fig.  589.)     Remove  the  button,  and  dry 


BRIDGE   DENTURES. 


6l3 


the  asbestos  in  a  flame  (Fig.  588).  When  perfectly  dry,  place  a 
sufficient  quantity  of  gold  scraps  in  the  die  made  in  the  asbestos, 
and  direct  the  blowpipe  flame  upon  it  until  melted,  inclining  the 
carbon  stick,  as  shown,  against  the  die  for  the  double  purpose  of 
confining  the  heat  and  warming  up  the  carbon  stick.  When  the 
gold  is  fused  into  a  button,  press  it  into  the  die  with  the  carbon 
stick  (Fig.  590).  Avoid  the  use  of  Hux  when  working  with  asbestos. 
To  build  up  a  cusp  to  make  a  perfect  articulation  in  this  manner, 
sealing-wax  must  be  used  instead  of  moldine,  as  in  the  method  of 
swaging  the  cusp.  Warm  the  button  before  applying  the  wax,  and 
with  a  warm  instrument  shape  the  cusp  as  desired. 


Fig.  588. 


Fig.  590. 


Gold  Central,  Lateral,  and  Cuspid  Crowns. — Select  from  the 
40  different  forms  in  the  set  that  which  is  most  suitable  to  the 
case  in  hand  (Fig.  591).  (The  forms  are  in  pairs,  showing  labial 
and  lingual  surfaces.)  Take  the  measurement  of  the  root  to  be 
crowned  with  one  of  the  annealed  copper  strips,  binding  the  strip 
around  the  tooth  with  pliers  and  pinching  the  joint  firmly  together. 
Trim  off  the  surplus  ends,  and  cut  the  measure  (Fig.  592,  a)  through 
the  center  (Fig.  592,  b),  then  bend  the  respective  halves  over  the 
lingual  and  labial  forms  selected,  at  the  necks,  with  the  cut  ends  of 
the  strips  resting  on  the  flat  of  the  plate  (Fig.  593).  If  the  meas- 
ure is  larger  than  the  form  selected,  build  the  latter  up  with  mold- 
ine until  the  space  between  the  form  and  strip  is  filled  (Fig.  593,  b). 
Avoid  getting  moldine  on  the  approximal  surface.  Remove  the 
strips,  dry  out  the  moldine  by  passing  through  a  flame  a  few  times, 
then  place  the  form  on  the  molding-plate  with  a  rubber  ring  around 
it.     Pour  Melotte's  metal  into  the  ring  as  in  forming  the  molar  or 


614 


MECHANICAL    DENTISTRY. 


bicuspid  cusp,  which  makes  a  die  of  the  two  sections,  lingual  and 
labial.  Make  a  lead  counter-die  and  proceed  as  directed  in  the 
making  of  a  molar  cusp,  swaging  the  sections  separately  (Fig-  594-)- 
Trim  off  the  surplus  plate    (Fig.   596),   and   square  the  opposing 


Fig.    591. 


Fig.    592. 


Fig.    594. 


/b 


Fig.  593. 


edges  of  the  two  sections  by  rubbing  them  over  a  dead  smooth 
file.  Bind  the  two  sections  together  with  wire  with  sufficient  solder 
and  flux  inside  (Figs.  597  and  598),  and  proceed  as  in  soldering 
an  ordinary  band.     With  a  small  mechanical  saw  cut  off  the  upper 


Fig.  595. 


Fig.  598. 


Fig.  596. 


Fig.  597. 


portion  where  the  tooth  begins  to  slope  back  (about  the  dotted  lines 
in  Fig.  598).  This  leaves  the  crown  as  shown  in  Fig.  595,  approxi- 
mal  and  labial  views.  Drive  on  the  root.  If  too  small,  place  on 
the  horn  of  an  anvil  and  enlarge  by  hammering;  if  too  large,  band 


BRIDGE    DENTURES. 


615 


the  root  in  the  same  manner  as  for  a  Richmond  crown,  grinding 
the  tooth  to  fit. 

Porcelain  Facings. — First  make  the  gold  crown  as  described. 
Select  a  porcelain  facing  suitable  for  the  case  (Fig.  600).  Place  the 
crown  on  the  root  in  the  mouth,  and  with  an  excavator  mark  on 
the  face  where  the  porcelain  is  to  appear.  Remove  the  crown  and 
saw  out,  so  that  the  facing  will  fit  loosely.  With  a  knife  bevel  the 
inner  edge  or  seat  for  the  facing  (Fig.  603).  Grind  the  facing  to 
fit  (Fig.  605).  Back  up  the  facing  with  No.  34  or  36  gage  pure 
gold,  punching  holes  in  the  backing  for  pins,  annealing  as  required 


Fig.  599. 


Fig.  600. 


Fig.  603. 


Fig.  605. 


Fig.  607. 


Fig.  608. 


to  readily  conform  it  to  the  tooth  (Figs.  601  and  602).  With  a 
sharp  knife  cut  a  barb  on  each  side  of  the  pins  in  the  facing,  and 
press  the  barbs  against  the  backing  (Fig.  604),  to  keep  the  backing 
in  place.  Burnish  down  the  edges  well,  being  careful  not  to  let 
the  backing  overlap  the  facing. 

Place  the  facing  in  the  space  prepared  for  it  in  the  crown  (Fig. 
606),  and  bind  the  two  together  (not  too  tight)  with  wire,  wrapping 
the  wire  directly  over  the  facing  with  asbestos  to  prevent  discolora- 
tion of  the  porcelain.  Flux  and  solder  by  holding  over  a  lamp  as 
in  the  case  of  a  band  (Fig.  599).     Then  finish  in  the  usual  way. 

If  it  is  desired  to  use  a  platinum  pin  for  anchorage,  as,  for  in- 


6i6 


MECHANICAL    DENTISTRY, 


stance,  a  Logan  pin,  bend  the  pins  in  the  facing-  sufficiently 
to  clamp  the  anchorage  pin,  and  insert  the  pin  through  the  gold 
crown  (Fig.  607),  finishing  as  before  described.  Fig.  608  shows 
a  finished  crown  so  made. 

The  Grinding  Surface  of  a  Bridge  in  One  Continuous  Piece. 
— After  having  crowned  the  teeth  for  the  attachment  of  the  bridge, 
take  a  bite  in  modeling  compound,  remove  the  compound,  place 
the  crowns  in  their  impressions,  make  a  cast  of  sand  and  plaster, 

Fig.  609. 


and  place  on  an  articulator;  now  put  moldine  between  the  abut- 
ments instead  of  wax,  and  get  the  articulation  with  cusp  buttons 
the  same  as  you  would  for  plate  teeth  (Fig.  609).  Then  to 
remove  the  buttons  without  destroying  the  articulation,  make  a 
cup  by  pouring  Melotte's  metal,  as  cool  as  it  will  flow,  on  the  face 
of  the  cusp  buttons.  Heat  the  pouring  lip  of  the  ladle  and  use  it 
to  smooth  out  the  half  congealed  metal,  much  as  you  would  a 
soldering  iron    (Fig.  610).     Then  place  a  thin  coating  of  moldine 

Fig.  610. 


upon  the  molding-plate.  Remove  the  cup  from  the  articulator 
with  the  cusp  buttons  in  place  (Fig.  610,  a).  Transfer  the  cusps 
by  inverting  the  molding-plate  (Fig.  611),  and  turn  the  cusp  but- 
tons out  upon  the  moldine  on  the  plate  with  the  grinding  surface 
up  (Fig.  611,  a),  and  they  will  occupy  the  same  relative  positions 
as  when  on  the  articulator. 

Now    place   the    large    rubber   ring   around   the   buttons   on   the 
plate,  and  proceed  to  make  a  die  with  Melotte's  metal.     When  cool, 


BRIDGE    DENTURES. 


6l7 


remove  the  buttons,  and  coat  the  face  of  the  die  with  whiting. 
Invert  the  die  and  raise  the  rubber  ring  sufficiently  high  on  it,  and 
make  a  counter-die  with  the  same  metal  by  pouring  as  cool  as  pos- 
sible (Fig.  613). 

This  gives  the  male  and  female  dies  with  which  to  swage  the 
continuous  grinding  surfaces.  Then  proceed  to  swage  the  gold 
plate  in   one   piece    (Fig.   614),    annealing  as   often   as   necessary. 

Fig.  612. 


Fig. 

6n. 

1 

= — =J 

a 

l 

%^~^<^^                1 

s^^~*^~~>s~^~*n   v.  ^y 

Trim  off  the  surplus  plate  (Fig.  614,  a),  and  place  in  position  on 
the  articulator.  Cut  the  cusps  out  on  the  buccal  face  to  avoid 
showing  the  gold  (Fig.  615),  grind  the  porcelain  facings  to  fit  the 
cusps,  and  back  with  gold,  No.  34  or  36,  letting  the  gold  come 
to  the  cutting  edge,  the  same  as  in  a  single  crown,  as  before 
described. 

If  there  is  a  space  between  the  cutting  edge  and  the  porcelain, 


Fig.  613. 


Fig.  614. 


Fig.  615. 


place  a  little  wax  in  the  joint  to  keep  out  the  plaster  investment, 
invest,  remove  the  wax  from  between  the  joints,  flux,  and  solder. 

Facings  for  an  All-gold  Bridge. — If  it  is  desired  to  make 
an  all-gold  bridge,  select  the  proper  facings  from  the  set,  make  a 
die  of  Melotte's  metal,  and  swage  up,  the  same  as  in  the  continu- 
ous bridge  before  described,  and  mount  gold  facings  in  place  of 
porcelain. 


6l8  MECHANICAL   DENTISTRY. 

Dr.  Parmly  Brown's  Method. — Dr.  E.  Parmly  Brown  de- 
scribes a  process  of  bridging  which  is  characterized  as  "  all-porce- 
lain." This  is  true  only  in  the  sense  that  no  metal  is  visible,  all 
parts  of  the  metal  framework  being  concealed  within  the  body  of 
the  porcelain.     The  method  is  as  follows : 

A  lateral  view  of  a  porcelain  crown,  with  a  platino-iridium  pin 
baked  in  position,  is  shown  in  Fig.  616.  The  pin  has  great  strength 
at  the  neck  of  the  tooth,  where  the  strain  is  greatest,  the  porcelain 
of  the  tooth  extending  up  on  to  it,  to  increase  the  strength ;  a  front 
view  of  the  same  crown  is  seen  in  Fig.  617,  showing  by  dotted  lines 
the  form  which  the  metal  occupies  in  the  crown  to  increase  the 
strength  of  the  attachment,  and  prevent  the  pin  from  approaching 
the  surface  in  thin  teeth. 

Fig.  618  is  a  view  of  the  two-pin  bicuspid  crown,  which  affords 

Fig.  616.  Fig.  617.  Fig.   618.  Fig.  619. 


a  pin  for  each  root  of  a  two-rooted  bicuspid,  the  staple  form  of 
the  pin,  shown  by  dotted  lines,  being  a  feature  of  strength. 

Fig.  619  is  a  view  of  a  bicuspid  crown  with  the  two  pins  pressed 
together,  making  a  single  pin  for  the  one  root. 

The  double  pin  in  the  bicuspid  crowns  prevents  the  loosening 
of  these  teeth  by  the  rotary  movements  of  mastication,  which  by 
means  of  the  two  cusps  exert  such  leverage  as  to  turn  and  break 
down  the  ordinary  crown  where  only  one  pin  is  used. 

This  bridge-work  system  has  the  metal  baked  invisibly  through 
the  body  of  the  teeth.  No  metal  shows  either  inside  or  outside 
of  the  dental  arch.  The  six  anterior  teeth  are  riveted  to  the 
platino-iridium  bar  by  the  ordinary  pins  of  plate  teeth,  which  are 
the  teeth  used  for  this  work.  The  bicuspids  and  molars  are  pre- 
pared by  grinding  a  slot  on  the  palatal  surfaces  of  the  teeth.  The 
bar,  which  is  squared  for  these  teeth,  instead  of  being  flattened,  as 
for  tbe  front  teeth,  is  inserted  into  this  groove  or  slot,  which 
should    be    ground    with    a    thin    corundum   wheel    to    fit    the    bar, 


BRIDGE    DENTURES. 


6l9 


which  can  be  barbed  to  make  proper  impingement.  It  is  then 
ready  to  receive  the  creamy  tooth  body,  which  at  this  juncture  is 
applied  to  the  palatal  surface  of  all  the  teeth,  completely  covering 
the  metal  and  giving  the  natural  contour  to  the  inner  surfaces.  A 
little  of  the  tooth-body  is  allowed  to  run  between  the  teeth,  unit- 
ing their  approximal  surfaces. 

In  this  work,  when  cross-pin  teeth  are  used,  the  pins  will  be 
ground  out  in  most  cases;  but  if  straight-pin  teeth  are  used  the 
pins  will  be  bent  over  the  bar.  We  will  give  a  few  illustrations  of 
the  many  ways  in  which  this  work  can  be  done. 

Fig.  620*  is  a  view  of  a  platino-iridium  bar  baked  on  to  a  plain 
plate  tooth,  by  first  riveting  the  flattened  bar  on  the  pins,  then 
applying  tooth  body  to  the  back,  completely  covering  bar  and  pins, 
and  then  baking  in  continuous-gum  furnace.     The  body,  mixed  to 


Pig.  620. 


Fig.  621. 


Fig.  622. 


! : .' 


a  creamy  consistency,  can  readily  be  applied,  and  after  being  held  a 
moment  over  a  spirit  lamp  is  ready  to  be  put  on  the  slide  and  baked. 

Cavities  or  fillings  are  usually  found  on  either  side  of  a  space 
made  by  the  loss  of  a  tooth  or  teeth  that  will  allow  the  insertion  of 
the  ends  of  the  metal  bar  and  the  thorough  impacting  of  gold 
around  them.  Amalgam  can  be  used  in  posterior  teeth  in  many 
cases,  or  gold  crowns  penetrated  by  the  bar,  as  in  Figs.  621  and 
622. 

In  Fig.  621,  No.  1  is  a  third  molar,  pulp  alive,  with  large  filling; 
No.  2  is  a  porcelain  bridge ;  No.  3  is  a  first  molar,  pulp  dead,  with 
a  metal  bar  entering  the  pulp  cavity. 


*  Fig.  620  is  incorrect  in  two  respects.  The  palatine  aspect  of  the  completed 
bicuspid  should  be  a  curved  line  from  the  palatine  cusp  to  the  cervicolabial  por- 
tion, and  not  make  a  saddle  over  the  ridge,  as  shown  in  the  cut,  which  would  be 
non-cleansible.  The  other  cut,  with  a  bar  riveted  on  to  a  bicuspid,  should  have 
the  bar  placed  in  a  groove  ground  into  the  center  of  the  teeth,  riveting  being 
done  to  incisors  and  cuspids  only. 


620 


MECHANICAL   DENTISTRY. 


In  Fig.  622.  No.  I  is  a  second  molar,  pulp  alive,  with  the  crown 
filling  of  gold  or  amalgam  retaining  the  bar;  No.  2  is  a  porcelain 
bridge ;  No.  3  is  a  gold  crown  with  bar  passing  through  crown  into 
root. 

Fig.  623  is  a  view  of  a  bridge  of  two  teeth — a  central  porce- 
lain crown  with  a  lateral  baked  into  it,  the  bar  and  pin  being  of  the 
same  piece,  bent  at  right  angles. 

In  Fig.  623,  No.  1  is  a  porcelain  crown  forming  part  of  the 
bridge ;  No.  2,  a  bridged  lateral  with  metal  bar  baked  through  it ; 
No.  3,  a  living  cuspid  with  a  metal  bar  running  in  the  center  of  a 
solid  gold  filling. 

Fig.  624  is  a  view  of  a  central  incisor  bridged  on  to  two  teeth 
whose  pulps  have  been  lost. 


Fig.  623. 


Fig.  624. 


Fig.  625. 


As  many  as  six  teeth  have  been  inserted  in  this  way  on  two 
central  roots,  and  the  posterior  end  of  the  invisible  metal  bar  run- 
ning through  the  six  teeth  worked  firmly  into  a  gold  filling  in  a 
molar — the  six  teeth  being  united  on  their  approximal  surfaces  by 
the  porcelain  running  between  them  at  the  baking.  The  backs  of 
such  teeth  must  be  given  a  curved  form  to  insure  a  cleanly  condi- 
tion. 

Fig.  625  is  a  view  of  the  attachment  of  the  bridge  to  a  tooth 
standing  alone,  where  the  tooth  has  a  gold  crown  attached,  or  the 
bar  is  worked  into  a  filling.  Nos.  1  and  3  are  teeth  on  a  porcelain 
bridge ;  No.  2  the  natural  tooth  over  which  the  bridge  is  saddled. 

All  teeth  for  this  bridge-work  should  be  ground  so  that  no  con- 
siderable portion  of  gum  would  be  covered,  the  teeth  just  touching 
the  gum  by  a  point  only  at  the  cervicolabial  portion. 


BRIDGE    DENTURES. 


621 


REMOVABLE   BRIDGE   DENTURES. 

As  has  been  intimated,  there  are  operators  who  prefer  bridge 
dentures  that  are  readily  removed  from  the  mouth  to  any  form  of 
stationary  fixture.  These  devices  may  be  made  so  that  the  dentist 
may  readily  remove  them  if  required  either  for  therapeutic  treat- 
ment, or  for  repair;  or  they  may  be  constructed  in  such  a  manner 
that  the  patient  may  remove  them  for  hygienic  reasons.  We  will 
first  consider  the  system  introduced  by  Dr.  R.  Walter  Starr,  whose 
description  is  about  as  follows : 

"  The  case  of  Mr.  W.  presented  difficulties  of  an  unusual  charac- 

Fig.  626. 


ter,  as  may  be  seen  by  inspecting  the  illustration,  Fig.  626,  which 
renders  detailed  description  unnecessary. 

"  It  will  be  observed  that  the  molars  and  the  left  second  bicuspid 
overhang  to  a  degree  that  would  make  the  taking  of  an  accurate  im- 
pression by  ordinary  methods  well-nigh  impossible.  After  a  careful 
study  of  the  case,  it  was  decided  that  two  separate  pieces  of  remov- 
able bridge-work  should  be  attempted,  and,  as  an  essential  prelimin- 
ary step,  the  overhanging  sides  of  the  molars  and  bicuspids  were 
ground  with  engine  corundum  wheels  and  points  until  those  sides 
were    made    much    less    inclined,    when    plaster    impressions    were 


622 


MECHANICAL    DENTISTRY. 


taken,  first  of  one  half,  and  then  of  the  other  half  of  the  jaw. 
Gold  cap  crowns  were  closely  fitted  over  the  molars,  left  second 
bicuspid,  right  first  bicuspid,  and  cuspid  stump.  Gold  crowns 
were  made  to  telescope  over  all  the  caps,  which  were  then,  by 
means  of  oxyphosphate  cement,  fixed  firmly  on  the  teeth.  Suit- 
able plate  teeth  were  selected,  fitted,  backed,  and  waxed  in  place 
between  the  telescoping  crowns.  After  hardening  the  wax  with 
cold  water  from  a  tooth  syringe,  the  pieces  were  carefully  removed,, 
invested,    and    soldered.     The   two   completed   bridges   were    easily 

Fig.  627. 


replaced  on  or  removed  from  the  supporting  capped  teeth,  and 
their  appearance  when  detached  is  correctly  shown  by  the  illus- 
tration, Fig.  627,  which  also  shows  the  capped  teeth  and  stumps.. 
This  figure  likewise  shows  the  results  of  the  novel  method  em- 
ployed in  crowning  the  incisors.  Gold  collars  were  fitted  tight  on 
the  necks  of  the  incisor  stumps,  and  the  new  style  porcelain  caps 
adjusted  in  the  collars,  and  set  in  the  oxyphosphate  cement  which 
had  been  packed  into  the  collars;  thus  at  the  same  time  fastening 
the  collars  on  the  stumps  and  the  caps  in  the  collars. 


BRIDGE   DENTURES. 


623 


"  Fig.  628  illustrates  the  finished  crowns  and  bridges,  which  latter 
were  secured  in  position  by  placing  a  small  piece  of  gutta-percha 
in  each  of  the  telescoping  cap  crowns,  which  were  then  warmed 
and  carefully  pressed  in  place — the  gutta-percha  filling  only  the 
spaces  between  the  flat  tops  of  the  caps  of  the  natural  teeth  and 
cuspid  caps  of  the  bridges. 

"  Whenever,  for  repair  or  for  any  other  purpose,  it  shall  become 
desirable  to  remove  one  of  the  bridges,  that  may  readily  be  done 
by  applying  a  hot  instrument  or  hot  air  to  the  caps  to  soften  the 

Fig.  628. 


gutta-percha  sufficiently  to  permit  the  telescoping  bridge  to  be  taken 
off. 

"  A  full  upper  vulcanite  denture  was  made  to  replace  the  old 
one,  which,  by  improper  occlusion,  had  thrown  the  full  force  of 
mastication  on  the  anterior  teeth  of  the  lower  jaw,  and  produced 
the  destructive  action  that  resulted  in  the  deplorable  loss  of  tooth 
substance  shown  in  Fig.  626.* 

"  The  next  case  also  presented  unusual  difficulties.  The  forward 
overhang  of  the  inferior  right  second  molar  was  so  excessive  that 
an  impression  could  hardly  be  taken,  until  with  corundum  wheels 


*  Dental  Cosmos,  vol.  xxviii. 


624 


MECHANICAL   DENTISTRY. 


and  points  the  sides  of  the  tooth  had  been  made  parallel,  or,  rather, 
slightly  tapering,  to  form  a  truncated  cone,  with  the  neck  as  a  base. 
The  molar  was  alive  and  sound,  but  the  crown  was  gone  from  the 
pulpless  cuspid,  which  I  suitably  shaped  by  means  of  my  root  trim- 
mers (Fig.  629). 

"  An  impression  was  then  taken,  the  cast  from  which  is  illus- 
trated by  Fig.  630.  A  seamless  gold  collar  was,  by  means  of  a 
slightly  tapering  mandrel,  made  to  exactly  fit  the  tapered  natural 
molar,  the  lower  edge  of  the  collar  cut  to  conform  to  the  gingival 
margin,  a  cap  piece  of  gold  plate  soldered  to  the  top  edge  of  the 
collar,  and  a  hole  drilled  through  the  center  of  the  completed  cap 


Fig.  629. 


(A).  Care  was  taken  to  so  fit  and  proportion  the  cap  that  it  would 
require  finally  pretty  hard  driving  to  send  it  home  on  the  tooth; 
but  first  there  was  fitted  to  the  cap  a  telescoping  seamless  collar, 
on  which  was  soldered  a  gold  plate,  with  cusps,  to  form  a  molar 
crown  as  shown.  The  molar  was  then  thoroughly  dried,  slightly 
painted  with  agate  cement,  and  the  cap,  A,  driven  hard  down  with 
a  flat  pine  stick  held  upon  it  and  struck  with  a  mallet,  the  hole  in 
the  cap  enabling  me  to  see  when  the  cap  was  quite  down.  The 
cuspid  was  then  likewise  fitted  with  a  seamless  gold  collar,  the  top 
edge  of  which  was  given  a  roof  shape,  as  seen  above  the  root  in 
Fig.  630.     A  piece  of  gold  received  a  corresponding  roof  shape, 


BRIDGE    DENTURES. 


62: 


had  a  short  section  of  gold  tubing  soldered  into  it,  and  was  trimmed 
to  the  outline  of  the  collar,  beside  which,  B,  its  form  is  seen,  and 
to  which  it  was  subsequently  soldered,  after  suitable  investment  to 
keep  the  parts  in  proper  place.  The  root  canal  had  been  pre- 
viously prepared  to  receive  the  tube,  which,  with  its  roofed  cap, 
was  with  stick  and  mallet  driven  hard  down  over  the  root.  A 
piece  of  gold  wire  exactly  fitting  the  tube  had  a  roof-shaped 
piece  of  properly  perforated  gold  plate  slipped  over  it  into  posi- 
tion on  the  root;  became  fixed  in  such  relation  by  a  drop  of  melted 
hard  wax;  was  removed,  invested,  soldered,  and  finished  in  such 
shape  that,  excepting  the  hollowness,  it  looked  like  the  tube  and 
cap  B. 

"  The  relations  of  the  occluding  teeth  had,  of  course,  been  de- 

Fig.  631. 


termined  by  an  articulating  model,  and  by  means  of  it  a  series  of 
seamless  gold  collars  and  cusp  crowns  were  adjusted  on  a  thin 
platinum  plate  fitted  on  the  cast  between  the  cuspid  and  second 
molar,  and  the  collars  soldered  to  the  plate  after  investment.  The 
truss  thus  formed  received  an  appropriate  finish  by  the  rounding 
and  smoothing  of  its  basal  borders.  A  plain  plate  cuspid  was 
backed  with  gold  plate  and  fitted  on  the  roof-plate,  to  which,  after 
determining  its  proper  occlusion,  it  was  secured  by  hard  wax,  re- 
moved, invested,  and  soldered.  It  was  then  put  into  the  tube  on 
the  root,  the  telescoping  cap  put  over  the  molar,  the  truss  put  in 
position  in  the  mouth,  and  the  whole  covered  with  plaster  and 
marble-dust,  contained  in  a  suitable  sectional  impression-tray, 
which  enabled  me  to  hold  the  mass  steadily  in  place  until  the  mix- 
ture was  sufficiently  hard  to  bring  away  cap  and  truss  and  roof- 
40 


626  MECHANICAL   DENTISTRY. 

plate  all  in  proper  position.  A  second  mixture  of  plaster  and 
marble-dust,  and  a  suitable  trimming  of  the  first  mixture  after  all 
was  hard,  sufficed  for  the  soldering  process  that  resulted  in  the 
denture  which,  when  finished,  appeared  as  shown  detached  at  C, 
Fig.  630,  and  mounted  on  the  cast  in  Fig.  631.  It  went  firmly  to 
place  in  the  mouth,  and  yet  was  removable  in  the  possible  event  of 
accident  to  the  denture,  or  for  readjustment  of  the  cusp  crowns, 
which  latter  could  easily  be  done  by  warming  the  piece  sufficiently 
to  soften  the  gutta-percha,  replacing  the  denture  on  its  anchorages, 
and  directing  the  proper  closure  of  the  occluding  teeth." 

Dr.  Parr's  Method. — The  following  is  a  method  of  construct- 
ing removable  bridge  dentures,  first  described  by  Dr.  H.  A.  Parr, 
in  the  Dental  Cosmos,  vol.  xxxi. 

In  the  construction,  adjustment,  and  placing  of  a  dental  substi- 
tute, one  of  the  first  considerations  is  its  immovability  in  position,, 
and  next  its  removability  for  cleansing  or  repair.  The  old  styles 
of  clasp  dentures  met  these  two  essential  requirements  when  the 
forms  and  relations  of  the  supporting  teeth  were  such  that  the 
clasps  would  firmly  embrace  those  natural  teeth  and  hold  the  close- 
fitting  plates  in  position.  But  the  clasped  teeth  soon  became  worn 
or  wasted,  and  in  consequence  the  loose  denture  lost  its  efficiency. 
Even  in  favorable  cases  the  inverted  cone  shape  of  nearly  every 
natural  tooth  made  it  a  matter  of  difficulty  to  secure  at  the  neck 
near  the  gum  a  tight  fit  of  the  springy  clasp,  which,  in  every  in- 
stance, must  have  been  large  enough  to  go  over  the  crown  of  the 
supporting  tooth.  Then,  too,  there  was  the  tendency  of  the  plate 
to  press  into  the  gum  and  so  become  loose  by  carrying  the  clasp 
to  a  yet  narrower  place  on  the  tooth.  In  many  cases,  moreover, 
the  supporting  teeth  inclined  toward  or  away  from  one  another,  and 
made  it  well-nigh  impossible  to  construct  a  plate  which  could  be 
sprung  into  place  and  yet  so  tightly  clasp  the  teeth  as  to  firmly  hold 
the  denture  in  position. 

The  object  in  devising  the  method  of  attachment  and  organiza- 
tion of  dental  substitutes  now  to  be  explained  was,  as  Dr.  Parr 
explains,  to  avoid  the  difficulties  mentioned,  which  will  be  made 
evident  in  the  following  description  of  two  practical  cases. 

Fig.  632  is  from  the  plaster  cast  of  a  lower  jaw  in  which  only 
the  lower  left  second  molar,  cuspid,  and  right  first  bicuspid  re- 
mained.    The  molar  and  bicuspid  were  fitted  with  gold  cap  crowns. 


BRIDGE   DENTURES. 


627 


Gold  sockets  were  prepared,  and  gold  tongues,  made  of  strips  of 
spring  gold  plate  having  their  ends  folded  upon  themselves  to 
form  spring  catches,  were  fitted  to  the  sockets.  The  cap  crowns 
were  placed  on  the  plaster  teeth,  the  boxes  or  sockets  hard  waxed 

Fig.   632. 


to  the  sides  of  the  crowns,  and  the  tongues  hard  waxed  to  a  piece 
of  stiff  wire  so  that  the  two  tongues  could  be  lifted  out  of  their 
sockets  without  breaking  either  the  tongues  from  the  wire  or  the 
sockets  from  the  crowns.  When  by  repeated  trials  this  could  be 
done,  the  crowns  and  sockets  were  taken  from  the  cast,  invested  in 

Fig.  633. 


plaster  and  marble-dust,  and  the  sockets  soldered  to  the  crowns. 
These  were  replaced  upon  the  cast  and  appeared  as  seen  in  Fig. 
632. 

The  tongues  were  then  placed  in  the  sockets,  the  artificial  teeth 


628 


MECHANICAL   DENTISTRY, 


arranged  on  the  cast  and  waxed  up  as  usual  for  vulcanite  work, 
taking  care  that  the  projecting  ends  of  the  tongues  were  so  im- 
bedded in  the  wax  that  they  would  be  held  firmly  when  the  piece 
should  be  removed  to  be  flashed.  It  is,  in  fact,  best  that  at  the 
outset  the  tongues  should  be  soldered  to   a  stout  gold  wire  bent 

Fig.  634. 


to  fit  the  cast,  so  that  the  wire  will  stiffen  the  waxed-up  piece,  and 
also  hold  the  tongues  more  securely  in  the  piece  during  and  after 
vulcanization. 

Fig.  633  shows  the  vulcanized  denture  in  place  on  the  cast. 

The  under  side  of  the  denture  is  shown  in  Fig.  634,  which  also 
makes  evident  the  forms  and  relations  of  the  tongues  which  hold 


Fig.  635. 


Fig.  636. 


the  denture  in  place.  The  parallelism  of  the  tongues  permits 
their  ready  removal  from  their  sockets,  no  matter  how  much  awry 
the  supporting  teeth  may  be.  The  bearing  of  the  denture  upon 
the  cap  crowns  admits  of  the  contact  of  the  denture  with  the 
gum  on  which  it  rests  but  cannot  be  pressed  into  because  of  the 


BRIDGE   DENTURES.  62CJ 

cap  crown  supports.  The  original  denture,  of  which  this  is  a  dupli- 
cate, is  now  in  satisfactory  use. 

Fig.  635  represents  the  articulated  cast  of  a  case  for  which  a 
similar  tongue  and  clasp  vulcanite  denture  was  made.  This  is  illus- 
trated in  Fig.  636,  which  needs  no  description.  Fig.  637  shows 
the  denture  in  place,  the  original  having  been  made  for  and  placed 
in  the  mouth  of  a  patient  exhibited  at  the  clinic  of  the  Odontolog- 
ical  Society  of  Pennsylvania,  at  Philadelphia,  in  December,  1888. 

These  are  simple  examples  of  a  class  of  work  having  a  wide  range 
of  application  and  capable  of  construction  without  the  trouble  and 
cost  of  all-gold  plate-work. 

The  sockets  and  spring  tongues  require  some  skill  and  nicety  of 
workmanship  to  insure  a  close  fit  of  the  one  in  the  other  so  that 
the  attachment  shall  be  firm,  yet  capable  of  easy-designed  detach- 
ment for  cleansing  or  repair. 

Fig.  637. 


A  notable  advantage  of  this  mode  of  constructing  dentures  for 
the  upper  jaw  is  manifest  in  the  fact  that  the  surface  of  the  plate 
which  rests  upon  the  gums  need  only  be  wide  enough  to  cover  the 
ridge,  and  thus  avoid  the  common  interference  of  artificial  dentures 
with  the  function  of  speech. 

Dr.  Davenport's  Method. — The  following  method  of  construct- 
ing partial  dentures,  described  by  Dr.  J.  L.  Davenport  in  the  Den- 
tal Cosmos  is  an  amplification  of  the  principle  of  attachment  in- 
volved in  the  process  just  considered. 

The  case  treated  was  one  where  the  only  teeth  remaining  in  the 
upper  jaw  were  the  six  front  teeth,  the  three  molars  on  the  right 
side,  and  the  first  bicuspid  on  the  left.  The  crowns  of  the  front 
teeth  were  wholly  obliterated  from  excessive  attrition  consequent 
on  the  loss  of  the  occluding  back  teeth,  necessitating  the  exclusive 
use  of  the  former  in  mastication,  as  shown  in  Fig.  638.    The  shorten- 


630 


MECHANICAL    DENTISTRY. 


ing  of  the  lower  teeth,  resulting  from  the  same  cause,  was  remedied 
by  building  them  up  to  a  uniform  height  with  crystal  gold,  Fig.  642, 
the  vacuities  in  the  lower  jaw  resulting  from  the  loss  of  the  left 
central  incisor  and  several  of  the  back  teeth  being  supplied  with 
substitutes  in  the  manner  hereinafter  described. 

For  this  case,  what  is  termed  a  "  combination  plate  and  movable 
bridge  "  was  constructed,  and  is  thus  described : 

"  The  two  superior  cuspid  roots  were  dressed  down  nearly  to  the 
gum  and  fitted  with  22-carat  gold  cap  crowns,  similar  to  those  de- 
scribed by  Dr.  J.  Rollo  Knapp.  After  these  had  been  placed  in 
position,  a  hole  was  drilled  through  each  cap  of  a  size  suited  to 
that  of  the  pulp  canal,  and  a  tube  of  iridium  and  platinum  was  ad- 

Fig.  638. 


justed  in  the  root  cap  and  waxed  in  position.  The  cap  and  tube 
were  then  taken  off  and  soldered,  great  care  being  taken  to  have 
the  tubes  enter  both  roots  perfectly  parallel.  These  were  perma- 
nently secured  in  the  roots  with  gutta-percha,  and  to  prevent  the 
caps  being  pulled  off,  the  top  of  each  tube  was  slit  down  a  trifle, 
and  after  insertion  was  bent  back  into  the  gutta-percha  with  a  warm 
instrument. 

'  The  incisor  roots  having  been  dressed  down  even  with  the 
gum  and  filled,  a  plaster  cast  was  taken  and  a  narrow  20-carat  gold 
plate  was  swaged  to  fit  over  the  ends  of  the  incisors  and  the  capped 
cuspids,  making  it  a  little  broader  where  it  had  to  rest  on  the  gum 
back  of  the  first  left  bicuspid  root.  A  hole  in  the  plate  was  then 
made  to  expose  the  root  of  the  first  left  bicuspid.     This  was  fitted 


BRIDGE   DENTURES. 


63I 


with  a  bifurcated  iridioplatinum  pin,  having  notched  sides,  and  a 
hammered  head  upon  its  lowered  end,  which  came  down  below  the 
root  about  }i  of  an  inch. 

"  A  thin  iridioplatinum  band  was  then  made  to  encircle  the  root, 
passing  just  under  the  gum  and  being  slightly  longer  than  the 
headed  pin.  This  band  was  perforated  with  two  rows  of  holes, 
from  without  inward,  giving  the  inner  surface  a  roughness  similar 
to  that  of  a  nutmeg  grater.  The  band  and  pin  were  then  made 
secure  to  the  root  with  a  non-shrinkable  copper  amalgam. 

"  Fig.  639  shows  the  upper  jaw  ready  for  the  plate. 

"  I  must  mention  here  that  this  method  of  lengthening  the  bi- 

Fig.  639. 


cuspid  is  not  original  with  me,  but  has  been  previously  described 
by  Dr.  E.  Parmly  Brown.  I  have,  however,  used  this  method 
several  times  on  very  frail  roots,  and  cemented  over  it  a  gold  cap 
crown. 

"  In  the  present  case,  after  the  amalgam  had  become  hard  and 
the  end  and  sides  had  been  polished,  a  gold  crown  was  fitted  over 
all  just  up  to  the  margin  of  the  gum,  and  in  close  contact  with  the 
end  of  the  band  and  amalgam.  This  crown  was  loose  enough  to 
admit  of  its  sliding  on  and  off,  though  with  just  enough  friction  to 
hold  it  in  place  when  at  rest.  This  gold  crown  was  then  placed  in 
position,  the  plate  also  inserted,  and  hard  wax  used  to  firmly  join 
the  two  in  the  mouth.     They  were  then  removed  and  soldered. 


6.^2 


MECHANICAL   DENTISTRY. 


"  Gold  pins  were  then  placed  through  holes  drilled  in  the  plate 
into  the  tubed  cuspids;  then  soldered  to  the  plate,  the  pins  being 
of  a  size  to  fit  the  tubes  accurately.  The  plate  was  also  provided 
with  a  wide  clasp  encircling  the  first  molar  on  the  right. 

"  The  plate  was   then   provided  with   a   gold  bar   about   %   of 

Fig.  640. 


an  inch  wide,  occluding  perfectly  with  the  lower  teeth,  and 
plain  teeth  soldered  in  place,  hiding  the  bar,  and  just  meeting 
the  gum  in  front  of  the  incisor  roots.  The  plate  rested  squarely 
against  the  capped  cuspids,  each  of  which  showed  a  narrow  band 
of  gold  when  the  plate  was  in  position.  As  finally  completed  (see 
Fig.  640)  this  was  the  most  perfectly  fitting  piece  I  ever  inserted, 

Fig.  641. 


requiring  great  care  in  its  removal,  and  yet  by  a  little  practice  the 
gentleman  was  able  to  remove  and  replace  it  quite  easily.  It  was 
also  as  firm  as  any  permanent  bridge  could  have  been,  though  it 
had  no  support  on  the  left  side  back  of  the  first  bicuspid. 

"  The  lower  jaw  was  supplied  with  a  double  20-carat  gold  plate, 
having  a  wide  clasp  on  the  first  right  bicuspid,  which,  after  being 


BRIDGE   DENTURES. 


633 


built  up,  presented  a  cone-shaped  top,  about  which  the  clasp  fitted 
so  as  to  rest  firmly  upon  the  end  of  the  tooth,  thus  preventing  in- 
jury to  the  gums  during  mastication. 

"  The  only  peculiarity  was  that  the  second  left  inferior  molar, 
being  abnormally  short,  though  well-formed  and  standing  upright, 
was  fitted  with  a  wide  clasp,  extending  about  ]/§  of  an  inch 
about  the  tooth,  and  a  piece  of  gold  plate  with  gold  cusps  was 
soldered  into  its  clasp,  covering  the  molar  crown  and  occluding 
with  the  molar  on  the  upper  plate.  (See  Fig.  641.)  This  not  only 
prevented  the  plate  from  being  bitten  down  unpleasantly  on  the 
gums  during  mastication,  but  enabled  me  to  use  a  shorter  molar 
upon  the  upper  than  I  otherwise  could  have  done,  and  better  al- 

FlG.  642. 


lowed  the  antero-posterior  and  lateral  movements  of  the  jaws.  The 
case  as  completed  is  shown  in  Fig.  642." 

Detachable  Bridge  by  the  Mandrel  System. — A  description 
of  two  or  three  methods  of  constructing  detachable  bridges  by  the 
mandrel  system  will  suffice  to  indicate  the  general  principles  in- 
volved. Having  these,  each  operator  will  find  it  an  easy  task  to 
devise  the  modifications  necessary  to  adapt  a  method  to  individual 
cases. 

The  first  method  is  especially  applicable  to  cases  where  both  ends 
of  the  bridge  are  attached  to  roots,  as,  for  example,  the  inferior 
cuspid  and  second  molar  roots  of  the  left  side,  the  intervening 
teeth  having  been  lost.  The  operation  is  conducted  as  described 
in  the  first  case  of  fixed  bridge-work  down  to  the  construction  of 


634 


MECHANICAL   DENTISTRY. 


the  truss,  for  which  in  this  method  square  gold  wire  is  used.  Hav- 
ing cut  the  wire  to  the  proper  length,  lav  it  upon  a  piece  of  gold 
plate  (about  No.  26,  American  gage)  of  the  same  length  and  full 
three  times  as  wide,  and,  placing  the  two  upon  the  lead  anvil,  with 
a  hammer  and  the  piece  of  file  before  used  drive  them  into  the 
lead.  This  will  form  the  plate  into  what  we  may  call  an  open  trunk, 
which  fits  the  square  wire.  Remove  the  two  from  the  lead  together, 
and,  without  separating  them,  curve  to  the  proper  shape  to  form 
the  truss.  Grind  crowns  having  vertical  holes,  like  the  Bonwill,  to 
fit,  and  having  determined  the  proper  points  for  the  supporting  pins, 
drill  through  both  trunk  and  bar  at  these  points.  Separate  the  bar 
from  the  trunk,  and  fit  and  solder  pins  to  the  bar.  Construct  small 
tubes  to  fit  the  pins,  ream  out  the  holes  through  the  trunk  to  admit 

Fig.  643. 


them,  and  set  the  tubes  with  solder  in  the  enlarged  holes  (Fig.  643). 
Fix  the  crowns  permanently  upon  the  tubes.  They  may  be 
mounted  in  any  of  the  approved  ways,  by  vulcanizing  or  by  the 
use  of  a  plastic  filling  material.  Wben  they  are  firmly  set,  place 
the  trunk  with  the  teeth  upon  the  bar  and  anchor  it  permanently 
as  already  described.     Fig.  644  shows  the  completed  work. 

"  In  this  method  the  truss  consists  of  the  bar  and  the  open  trunk 
which  covers  three  sides  of  it.  The  bar  is,  of  course,  permanently 
attached  to  the  roots  of  the  molar  and  cuspid,  but  the  trunk  with 
the  teeth  can  be  removed  at  any  time. 

"  The  second  method  of  constructing  a  detachable  bridge  is 
applicable  to  cases  where  one  or  both  of  the  supports  or  piers  are 
sound  teeth.     In  the  case  adduced  for  illustration,  the  right  inferior 


BRIDGE   DENTURES. 


^\ 


•cuspid  crown  was  decayed,  and  both  of  the  bicuspids  and  the  first 
molar  were  absent.  The  supports  for  the  bridge  were  the  sound 
second  molar  and  the  cuspid  root.  After  the  cuspid  root  was 
prepared  and  banded,  the  crown  of  the  molar  was  reduced  very 
slightly,  not  sufficient  to  destroy  the  enamel,  but  just  enough  to 
permit  a  collar  properly  fitted  to  pass  over  it.  A  collar  somewhat 
wider  than  the  length  of  the  crown  from  grinding  surface  to  neck 
was  fitted  and  cut  to  the  proper  width.  Two  lugs  were  then  soldered 
upon  the  anterior  and  posterior  sides  and  bent  to  fit  into  the  ap- 
proximal  fissures,  which  were  slightly  cut  out  to  admit  them.  An 
impression  was  taken,  the  collar  coming  away  in  the  plaster,  and  a 
cast  was  made  with  the  collar  in  position.  A  coned  tube  was  then 
made  for  the  root  of  the  cuspid  and  a  coned  pin  fitted  into  it.     A 

Fig.  644. 


truss  of  half  round  wire  was  made,  to  which  the  collar,  coned  pin, 
and  the  molar  were  next  soldered  (Fig.  645).  A  half-clasp  to  grasp 
the  lateral  was  next  soldered  to  the  end  of  the  truss,  to  be  supported 
by  the  cuspid.  The  object  of  this  clasp  was  to  guard ^ against  the 
teeth  being  thrown  out  of  proper  alignment  by  the  force  of  masti- 
cation. Bonwill  crowns  were  then  vulcanized  to  the  truss,  after 
their  supporting  pins  had  been  fitted  and  soldered  to  it.  (Counter- 
sunk crowns  can  be  used  as  well  in  the  same  way.  Plain  plate 
teeth  may  also  be  used  in  this  style  of  work,  in  which  event  they 
are  to  be  soldered  to  the  truss.)  The  bridge  was  then  ready  to  be 
set,  which  was  accomplished  in  the  following  manner :  The  cuspid 
root  was  nearly  filled  with  oxyphosphate,  and  the  coned  tube  was 
placed  upon  the  pin.  The  band  was  put  on  the  molar,  and  the 
-  coned  pin,  with  the  tube  upon  it,  was  forced  into  the  plastic  in  the 


636 


MECHANICAL    DENTISTRY. 


cuspid  root.  As  soon  as  this  became  set,  the  tube  was  held  perma- 
nently, while  the  bridge  itself  could  be  removed  whenever  desired 
(Fig.  646). 

"  This  method  of  fixing  the  tube  allows  considerable  range  in  its 
adjustment.  In  soldering  the  coned  pin  to  the  truss,  care  should 
be  taken  to  set  it  at  an  angle  exactly  parallel  to  the  axis  of  the- 
molar;  otherwise  there  will  be  difficulty  in  removing  the  bridge. 


Fig.  645. 


Fig.   646. 


"  The  third  style  of  detachable  bridge-work  to  be  described  in- 
volves the  use  of  cusp  crowns  (Fig.  647)  for  supporting  posts  or 
piers.  Suppose  a  case  similar  to  that  just  described,  where  a 
bridge  is  required  to  extend  from  the  right  inferior  cuspid  to  the 
right  inferior  second  molar,  with  only  the  roots  of  the  two  teeth 
named  as  supports.  Prepare  the  roots  and  pulp  chamber.  Set 
screw-posts  into  the  dentine  for  anchorage,  or  as  retaining  pins,  and 

Fig.  647. 


fit  the  collars,  using  sizes  wide  enough  to  form  the  walls  of  the- 
crowns.  Fill  the  pulp  chamber  and  about  two-thirds  of  the  depth 
of  the  collars  with  a  plastic  filling  material,  packing  it  well  around 
the  retaining  posts.  Select  suitable  cusp  crowns  for  the  molar  and 
cuspid  and  place  them  in  the  ends  of  the  bands  to  ascertain  the 
occlusion.  If  too  long,  shorten  the  cusps  or  reduce  the  bands  with 
engine  corundum  wheels,  and  when  the  correct  articulation  is  found 


BRIDGE   DENTURES. 


637 


form  a  small  square  shoulder  in  the  lingual  edge  of  the  cuspid  and 
in  the  posterior  grinding  surface  of  the  molar.  Fill  the  remaining 
portion  of  the  collars  with  plastic  mixed  somewhat  thinner  than 
the  first  lot,  and  set  the  cusp  crowns  in  position.  If  there  are  an- 
tagonizing teeth,  the  mere  closing  of  the  patient's  jaws  will  force 
the  crowns  to  place.  If  there  are  no  antagonizing  teeth,  the  crowns 
•can  be  readily  tapped  to  place  with  the  mallet,  using  a  piece  of 
wood  as  a  driver.  Allow  the  filling  material  to  set  firmly,  trimming 
off  any  excess  which  may  exude  around  the  collars.  Bridge  sup- 
ports or  piers  constructed  on  this  plan  are  strong  and  durable,  and 
likely  to  withstand  any  strain.  Take  an  impression  and  proceed 
to   fit   seamless   collars   to   telescope   over   those   already    set    upon 


Fig.  648. 


Fig.  649. 


the  cuspid  and  second  molar  roots.  It  will  be  remembered  that 
these  collars  are  so  made  that  each  size  telescopes  into  the  next 
higher  series.  If  the  proper  sizes  are  selected  for  the  outside  bands, 
the  work  of  fitting  is  readily  and  quickly  accomplished,  forming 
tubes  which  slide  easily  over  the  supporting  piers,  and  at  the  same 
time  fit  closely.  It  is  only  necessary  to  take  care  in  shaping  the 
tubes  not  to  drive  them  too  far  up  on  the  mandrels,  and  thus  stretch 
them  so  as  to  destroy  the  fit.  To  the  outer  end  of  each  of  the  tubes 
solder  a  small  piece  of  gold  plate,  forming  partial  caps  so  placed 
as  to  rest  when  in  position  upon  the  shoulders  previously  cut  in  the 
cusp  crowns.  Adjust  a  truss  bar  of  half  round  gold  wire,  to  the 
ends  of  which  solder  the  tubes  (Fig.  648).     The  truss  is  now  ready 


638'  MECHANICAL   DENTISTRY. 

for  the  teeth,  which  may  be  of  any  of  the  forms  used  for  this  pur- 
pose, and  they  may  be  attached  to  the  bar  in  any  way  desired. 
One  of  the  strongest  attachments  is  vulcanite. 

'*  An  easy  modification  of  this  plan  is  readily  adapted  to  cases 
where  only  a  small  space  is  to  be  filled  and  one  end  of  the  bridge 
is  to  be  supported  by  a  sound  tooth.  Thus,  suppose  it  is  desired  to 
bridge  a  space  formerly  occupied  by  the  two  inferior  left  bicuspids, 
the  crown  of  the  first  molar  being  a  mere  shell.  The  operation  would 
be  essentially  the  same  as  in  the  previous  case,  except  that  the  sound 
cuspid  would  be  utilized  for  one  of  the  piers,  as  follows :  Fit  a  seam- 
less collar,  cut  out  a  portion  of  it  so  that  it  will  embrace  only  about 
two-thirds  of  the  cuspid  crown,  and  solder  a  partial  cap  or  cover  to 
it  (Fig.  649).  Or,  the  cuspid  crown  may  be  separated  from  the  lat- 
eral incisor  with  a  diamond  disc  and  the  collar  allowed  to  embrace 
the  whole  crown. 

"  The  great  desideratum  in  constructing  a  piece  of  bridge-work 
is,  of  course,  the  securing  of  perfect  usefulness  in  mastication  and 
speech,  combined  with  absolute  comfort  and  cleanliness.  The 
closer  a  bridge  approaches  that  condition  where  its  wearer  loses 
consciousness  of  its  presence  in  his  mouth,  the  nearer  perfection  it 
is.  Scarcely  less  important,  however,  is  the  necessity  of  providing 
for  repair.  Accidents  will  occur,  and  the  system  which  superadds 
to  usefulness,  comfort,  and  beauty,  ready  facility  for  repairing  "break- 
ages, is  by  so  much  superior  to  those  which  make  no  such  provision. 
The  place  of  a  crown  broken  from  a  bridge  constructed  by  any  of 
the  methods  above  described  can  be  easily  supplied,  and  the  piece 
when  repaired  will  be  as  strong  and  serviceable  as  it  was  originally." 

Dr.  Condit's  System. — The  method  devised  by  Dr.  A.  S. 
Condit  is  the  combination  of  removable  plate  with  gold  or 
Richmond  crowns,  which  are  cemented  upon  the  natural  teeth  or 
roots,  contiguous  to  the  space  to  be  filled  with  the  artificial  sub- 
stitute. The  plate  is  made  to  rest  upon  the  gums,  and  held  firmly 
in  place  by  means  of  an  attachment,  part  of  which  is  placed  upon 
the  crowns  and  a  part  in  the  plate. 

The  construction  of  the  attachment  is  such  that  when  the  work 
i^  in  place  it  cannot  be  detached  except  by  a  straight  up  or  down 
pull,  nor  can  there  be  any  lateral  movement.  It  is  also  claimed  to 
have  sufficient  tension  to  hold  the  work  securely  in  place,  yet  not 
so  firmly  but  that  it  can  be  easily  removed  by  the  patient. 


BRIDGE    DENTURES. 


639 


By  the  use  of  this  method  the  natural  teeth  are  sealed  up  and 
protected  from  the  attrition  of  the  plate,  and  they  are  held  firmly 
in  their  normal  position  and,  Dr.  Condit  says,  are  not  moved  out  of 
line  during  mastication. 

A  prominent  feature  of  this  work  is  that  the  bearing  is  supposed 
to  be  equally  divided  between  the  teeth  attached  to,  and  the  ridge. 

Figs.  650  and  651  represent  the  loss  of  the  lower  incisors.  The 
advantage  in  using  the  method  for  such  cases  is  that  the  cuspids 
are  held  firmly  in  their  normal  position  and  undue  pressure  is  re- 
leased from  the  gums. 

If  the  ridge  had  to  bear  the  entire  weight  of  the  plate,  the  gums 
would  soon  be  pressed  away  from  the  cuspids,  and  the  teeth  would 
move  out  of  line. 

In  upper  cases,  where  bicuspids   and  molars  have  been  lost  on 


Fig.  650. 


Fig.  651. 


both  sides,  as  shown  in  Figs.  652  and  653,  the  work  can  be  con- 
structed by  connecting  the  sides  with  a  narrow  plate  across  the 
center  of  the  palate,  or  by  skirting  the  anterior  teeth  with  a  narrow 
strip  of  plate,  and  the  same  object  be  accomplished  as  when  the 
entire  palate  is  covered. 

This  method  is  considered  by  Dr.  Condit  to  be  applicable  in 
one-attachment  cases,  such  as  are  shown  in  Figs.  654  and  655.  He 
suggests,  however,  that  in  making  this  appliance  a  small,  soft-rub- 
ber washer  should  be  placed  over  the  pin  in  the  attachment,  so  that 
the  greatest  strain  should  be  brought  upon  the  ridge,  the  attach- 
ment merely  giving  it  stability. 

The  directions  given  by  Dr.  Condit  for  the  construction  of  this 
class  of  denture  are  about  as  follows  : 

One-attachment  Case. — First  fit  a  gold  cap  crown  to  the  tooth, 


640 


MECHANICAL    DENTISTRY, 


contiguous  to  the  space  to  be  occupied  by  the  piece,  with  the  same 
accuracy  as  for  an  ordinary  bridge.     When  in  place,  mark  with  a 


Fig.  652. 


Fig.  653. 


sharp  instrument  the  position  for  the  tube  (1,  Fig.  656),  which 
should  be  at  the  posterior  lingual  side,  far  enough  from  the  buccal 
to  avoid  interference  with  the  artificial  teeth,  and  yet  not  so  far  as 


BRIDGE   DENTURES. 


64I 


to  make  an  undue  prominence  on  the  lingual  side.  The  crown  or 
band  is  now  removed  from  the  mouth  and  the  tube  (1,  Fig.  656) 
attached  with  18-carat  gold  solder,  using  no  more  than  just  suf- 
ficient solder  to  hold  it  securely.  To  properly  do  this  the  tube 
should  be  placed  on  one  point  of  a  pair  of  soldering  pliers,  with  the 
open  side  out,  as  shown  in  Figs.  658  and  659,  and  held  as  nearly 
vertical  in  its  relation  to  the  crown  as  possible.  If  the  crowned 
tooth  leans  to  the  one  side  or  the  other,  so  that  it  is  necessary  in 
giving  the  tube  its  vertical  position  to  stand  it  away  from  the  crown 
at  either  the  coronal  or  gingival  ends,  it  may  easily  be  accom- 
plished by  bending  the  points  of  the  pliers  out  or  in,  as  is  clearly 
shown   in   Figs.   658  and   659.     The  tube   now   being   soldered   in 


Fig.    654. 


Fig.   655. 


place,  should  be  spread  very  slightly  by  passing  a  round  instru- 
ment through  it — to  allow  the  pin  and  shield  (Fig.  656)  to  slip 
easily  on  and  off — and  the  crown  or  band  returned  to  the  tooth  with 
the  pin  and  shield  in  position. 

If  the  articulation  is  interfered  with,  the  tube  may  be  dressed 
down  from  the  coronal  end,  and  the  pin  and  shield  correspondingly 
ground  off  from  the  gingival  end,  repointing  the  pin  by  carefully 
running  a  small  pear-shaped  bur  around  between  it  and  the  shield. 

The  crown  or  band  should  now  be  cemented  to  the  tooth  and  the 
cement  allowed  to  thoroughly  harden,  when  the  pin  and  shield  are 
again  placed   in  position  and  the  bite   and  impression   taken.     Be 
sure  to  take  the  bite  before  taking  the  impression. 
41 


6-12 


MECHANICAL   DENTISTRY. 


If  the  pin  and  shield  do  not  come  away  with  the  impression  they 
must  be  removed  from  the  tube  and  carefully  placed  in  proper 
position  in  the  impression,  which  should  be  varnished  or  otherwise 
prepared  for  pouring  the  model.  Before  pouring-,  however,  the 
long  tube  (Fig.  657)  is  filled  with  plaster  and  slipped  over  the  pin 
in  the  shield,  the  lug  (A)  projecting  from  the  open  side  of  the  shield. 
This  long  tube  prevents  any  possible  displacement  of  the  shield 
after  the  model  is  poured,  and  the  filling  with  plaster  prevents  the 
vulcanite  from  filling  the  shield. 

The  model  is  now  poured  in  the  usual  manner  and  placed  on  the 
articulator;  teeth  arranged,  flasked,  and  finished  as  in  any  ordinary 
denture — except  before  packing  the  vulcanite,  the  point  of  the  lug 
(A)  attached  to  the  shield  (Fig.  656)  may  be  bent  slightly,  in  such 
wise  as  to  give  it  firmer  hold  in  the  plate.    After  vulcanizing,  the  tube 


Fig.   656. 


Fig.   658. 


Fig.   659. 


(Fig.  657)  is  removed  from  the  shield  and  the  piece  finished.  Pinch 
tube  (1,  Fig.  656)  on  the  crown  very  slightly  and  adjust  the  work. 

Tzvo-attachmcnt  Case. — The  proceedings  are  identical,  except  in 
the  matter  of  attaching  the  tubes  to  the  crowns  or  bands.  In  these 
cases  the  crowns  are  properly  fitted  and  placed  upon  the  teeth 
selected  for  attachments.  Then  an  impression  must  be  taken  and 
the  crowns  removed  from  the  teeth  and  placed  in  their  relative  posi- 
tions in  the  impression  and  a  model  made.  (Wooden  cores  about 
y2  of  an  inch  in  length  may  be  fitted  rather  loosely  in  the  crowns 
before  pouring,  to  permit  their  easy  removal  from  the  model.) 

After  the  model  is  secured,  crowns  in  place  thereon,  the  guide 
(Fig.  660)  is  adjusted  with  reference  to  the  proper  placing  of  the 
tubes  (1,  Fig.  656),  as  directed  in  the  one-attachment  case,  and 
fixed  with  the  set-screws.  (One  post  of  the  guide  is  adjustable 
to  allow  for  any  variation  in  the  height  of  the  crown.)  The  tubes 
are  now  placed  upon  the  ends  of  the  guide  posts,  with  the  open 


BRIDGE   DENTURES. 


643 


side  away  from  the  crowns.  The  screw  (B),  Fig.  660,  is  run  down 
until  the  point  touches  the  model,  when  a  little  melted  beeswax 
dropped  at  the  point  will  hold  the  whole  in  position  until  the  tubes 
(1,  Fig.  656)  are  waxed  with  hard  wax  to  the  crowns.  After  which 
the  center  screw  (B),  Fig.  660,  may  be  carefully  turned  to  the  left, 
releasing  it  from  the  wax,  and  the  guide  may  be  removed  from  the 
tubes.  The  crowns  are  then  removed  from  the  model,  invested  in 
plaster  and  sand,  and  tubes  soldered. 

In  cementing  the  crowns  on  the  teeth,  in  the  mouth,  before  the 
cement  hardens,  it  is  well  to  remove  the  center  screw  from  the 
guide  and  test  the  tubes  to  be  sure  that  the  crowns  have  gone  back 
^exactly  to  their  proper  places  on  the  teeth. 

Attachments  for  Porcelain  Work. — The  crowns  and  attachments 


Fig.  660. 


are  made  and  adjusted  in  the  manner  just  described.  After  cement- 
ing them  to  the  teeth,  platinum  shields,  the  same  as  Fig.  656,  lacking 
the  lug  A,  are  placed  over  the  tubes  and  impression  taken.  If  the 
shields  do  not  come  away  with  the  impression  they  must  be  re- 
moved and  placed  in  their  proper  places  therein. 

Pour  your  model  now  with  the  view  to  making  metal  dies 
for  swaging. 

The  plate  must  be  swaged  to  fit  with  the  utmost  nicety  around 
the  shields  and  teeth. 

If  several  teeth  must  be  skirted,  to  give  the  requisite  strength  an 
extra  piece  of  28  gage  platinum  should  be  swaged  and  soldered  to 
the  plate  with  pure  gold. 

After   swaging,   remove   the   shields    from   the   model   and   place 


644  MECHANICAL   DENTISTRY. 

them  in  position  in  the  mouth ;  then  try  in  the  plate ;  if  swaged  to  a 
proper  fit,  take  impression  with  plate  and  shields  in  position.  If 
they  come  out  with  the  impression,  a  platinum  tube,  the  same  as 
Fig.  651,  is  placed  in  the  shield  and  a  plaster  and  sand  model  is 
poured.  When  separated,  solder  the  shields  to  the  plate,  using  pure 
gold  solder,  and  again  try  in  the  mouth.  If  care  has  been  exercised 
in  every  detail,  the  plate  must  fit  snugly,  when  wax  may  be  inserted 
and  the  bite  secured.  Remove  the  wax  and  plate  together ;  tack 
asbestos  fiber,  soaked  in  water,  into  the  shield  until  filled ;  then  place 
on  the  articulator,  and  proceed  as  in  the  case  of  any  ordinary  con- 
tinuous-gum piece. 

Attachments  for  gold  work  are  made  identically  as  described  for 
porcelain  above.  The  shields  for  gold  work  are  made  of  20-carat 
gold,  soldered  with  20-carat  solder.  Thus  the  gold  attachments 
made  for  vulcanite  work  cannot  be  used  in  connection  with  gold 
plates,  as  the  shields  are  of  18-carat  gold,  the  pins  16-carat,  and 
soldered  with  14-carat  solder. 

Attachments  for  cast  aluminium  are  made  exactly  as  for  vulcanite, 
described  above,  using,  however,  the  platinum  shields. 

Dr.  Carr's  Method. — A  system  of  making  anchored,  adjustable, 
and  removable  dentures  was  devised  about  six  years  ago  by  Dr.  C. 
M.  Carr,  of  Salt  Lake  City,  Utah.  In  describing  his  work  he  says : 
"  I  have  adopted  the  name  '  anchored,  adjustable,  and  removable  den- 
ture,' because  it  better  fits  the  work  than  either  '  plate  '  or  '  bridge.' 
While  the  method  partakes  partially  of  both  bridge-  and  plate-work, 
yet  it  is  neither  of  them,  the  palate  never  being  covered  and  the 
teeth  or  roots  used  for  anchorage  having  no  excessive  pressure  or 
lateral  strain  placed  on  them.  There  is,  however,  a  light  and  yield- 
ing pressure  placed  upon  the  roots  during  mastication — an  inter- 
mittent pressure,  which  nature  seems  to  require  to  sustain  a  healthy 
union  between  any  root  and  the  alveoli.  This  intermittent  pressure 
is  imparted  by  the  little  spiral  spring,  which  is  the  secret  of  my 
method,  everything  else  being  employed  to  accommodate  it." 

In  illustrating  this  form  of  denture  we  have  selected  an  extreme 
case,  one  where  other  forms  seem  almost  barred  out.  It  is  a  fac- 
simile of  a  case  now  being  worn  by  a  lady  in  California.  The 
mouth  was  such  that  an  adhesive  plate  was  not  very  successful,  and 
it  was  a  great  desire  of  the  patient  to  have  the  palate  free  and  un- 
encumbered, as  is  frequently  the  case  with  speakers  and  singers. 


BRIDGE   DENTURES.  645 

All  the  teeth  having  been  lost,  the  first  thing  done  was  to  implant 
two  roots,  one  on  either  side,  in  about  the  center  of  the  ridge. 
These  roots,  however,  were  prepared  for  the  reception  of  the 
posts,  and  filled  with  gutta-percha  before  being  implanted.  After 
the  roots  became  thoroughly  attached,  an  impression  was  taken ; 
the  imprints  of  the  roots  were  enlarged  about  T\  of  an  inch  in 
same  before  the  cast  was  run.  This  is  done  so  that  the  roots 
will  appear  larger  on  the  cast  and  die,  both  in  height  and  breadth, 
and  when  the  saddle  or  base  (Fig.  662)  is  swaged  and  placed 
upon  the  ridge  in  the  mouth  there  will  be  a  space  between 
the  chambers  on  the  roots  and  the  roots  themselves.  This  being 
accomplished,  a  little  warm  wax  was  placed  in  these  chambers 
and  the  saddle  pressed  firmly  into  position  against  the  gum  tissue. 
In  this  way  the  exact  location  (by  impression  of  the  end  of  root  in 
wax)  of  the  tube  in  the  root  is  secured.  Then,  with  a  plate  punch, 
a  hole  is  made  in  the  exact  center  of  the  impression  of  the  end  of 
tube,  after  which  two  other  holes  are  punched,  one  on  either  side 
of  the  first,  or  center  one;  then  with  a  fissure  drill  on  the  dental 
engine  cut  the  three  together,  making  a  slot,  as  shown  on  the  left 
side  of  Fig.  662,  through  which  the  T  head  of  the  anchorage  stud 
(A)  will  pass.  Then,  as  it  is  necessary  to  prevent  the  T  head  of 
stud  A  from  rotating  or  moving  during  mastication,  and  thus  re- 
leasing the  denture,  a  segment  of  a  disc  is  soldered  on  each  side  of 
the  slot,  as  shown  at  H  in  Fig.  662,  and  a  cross-cut  filed,  with  a 
very  small  round  file,  directly  across  these  two  segments  at  right 
angles  with  the  slot.  It  is  in  this  small  cross-cut  that  the  T  head, 
the  under  portion  of  which  is  half-round,  will  rest  when  the  denture 
is  in  position. 

The  next  step  is  to  secure  the  outer  tube,  with  lid  at  top  for 
closing  same  (F,  Figs.  662  and  670),  in  the  exact  location  for  the 
free  working  of  the  adjusting  stud  (A).  After  this  is  located  cor- 
rectly and  soldered  in  position,  the  saddle  is  ready  to  receive  the 
teeth. 

For  this  purpose  place  the  saddle  (Fig.  662)  in  the  mouth,  and  with 
a  key  (Fig.  672)  rotate  stud  A  one-quarter  turn  in  tube  (F),  and  the 
T  head  will  stand  directly  across  slot  and  rest  in  cross-cut  H  (Fig. 
662),  thus  locking  denture  securely  against  the  gum  so  far  as  any 
liability  of  being  thrown  out  of  position  is  concerned.  And  yet  these 
roots  beneath  are  not  in  actual  contact  with  the  saddle,  the  counter- 


646 


MECHANICAL    DENTISTRY 


Fig.    661. 


Fig.    662. 


Cast  of  upper  jaw  ready  to  receive 
the  denture. 


Saddle  formed  to  receive  teeth 
for  upper  denture. 


Fig.  663. 


Upper  denture  in  position. 


Fig.  664. 


Straight  root 
attachment 
in  position. 


Fig.  665. 


Transverse  section  of 
molar  root  attach- 
ment   in    position. 


Fig.  666. 


'fi^ 


Third  molar  attached 
where  there  is  no 
occluding    tooth. 


BRIDGE   DENTURES. 


647 


sunk  chambers  leaving  a  space  over  and  around  hem.  The  saddle 
is  now  between  the  little  washer  B  and  the  T  head  A,  Fig.  667 ;  the 
spring  C  is  under  the  washer  B  and  encircles  the  shaft  of  the  stud 
in  the  root  down  to  the  threaded  portion  (see  Fig.  668)  and  rests  on 
a  shoulder  in  tube  between  E  and  D.  Now,  during  mastication  the 
gum  still  admits  of  some  motion  of  the  denture,  it  being  of  a  soft  and 


Fig.    667. 


Single      straight 
root  attachment. 


Fig.    668. 


Adjusting    stud,    spiral 
spring  and  washer. 


Fig.    669. 


Molar   root 
attachment. 


Fig.    670. 


Tube     with 
spring   lid. 


Fig.  6; 


yielding  nature,  so  that  when  there  is  any  pressure  placed  on  the  piece 
the  spring  beneath  is  compressed  slightly,  imparting  a  light  and  yield- 
ing pressure  to  the  root  or  roots  beneath.  This  intermittent  pres- 
sure seems  to  be  what  nature  requires  to  sustain  a  healthy  union  be- 
tween the  roots  and  the  process.  Without  the  spring  there  would 
not  be  any  pressure  on  the  roots  at  any  time,  and  the  weight  of  the 
denture  would  eventually  draw  the  roots  from 
their  sockets,  until  the  denture  would  come  in 
contact  with  them  during  mastication,  after  which 
the  pressure  of  mastication  of  the  whole  case 
would  be  on  the  roots,  which  nature  would  never 
tolerate. 

The  case  completed  and  in  position  is  shown 
in  Fig.  663. 

In  attaching  this  system  to  a  first  molar  root, 
Dr.  Carr  describes  his  process  as  follows :  "  In 
this  case  we  must  utilize  breadth  in  place  of  depth 
to  accommodate  the  attachment.  The  spring  is 
what  we  wish  to  accommodate.  Now,  the  root 
being  found  in  position  and  the  second  molar 
missing,  we  grind  the  root  down  until  it  just 
stands  flush  with  the  gum ;  then  chamber  out  to  near  the  bifurcation 
of  the  roots,  making  the  chamber  of  considerably  larger  diameter 


Posterior  end 
saddle,  held  in 
position  against 
■  gum  by  means  of 
platinized  gold 
pin  set  into  the 
tooth  or  filling. 


648 


MECHANICAL   DENTISTRY. 


Fig.  672. 


than  for  the  other  form  (compare  Figs.  664  and  665).  A  piece  of 
gold  plate  covers  the  end  of  the  root  the  same  as  in  the  other  case, 
with  larger  hole  through  same.  In  this  hole  is  placed  an  internally 
threaded  tube,  adapted  to  engage  another  externally  threaded  tube 
or  cup ;  for  one  end  of  this  second  tube  is  closed,  and  in  the  center 
of  this  closed  end  is  soldered  the  adjusting  stud  with  washer 
encircling  same  next  to  T  head,  A.  The  spring  interposed  between 
washer  and  bottom  of  cup  (Fig.  669)  imparts  the  intermittent 
pressure  as  in  the  other  form  of  attachment. 
Now  this  same  form  is  used  for  wisdom  teeth 
attachments  where  there  is  no  occluding  mate 
and  it  becomes  necessary  to  impart  an  artificial 
pressure  to  overcome  gravity.  In  this  case  it  is 
either  anchored  in  a  large  approximal  filling  or 
soldered  to  a  gold  crown.  (See  Fig.  666.)  The 
most  common  case  to  be  met  with  is  the  pin  in 
a  molar  left  protruding  to  engage  the  posterior 
end  of  the  saddle;  this  is  the  form  that  is  appli- 
cable to  all  molar  cases  except  as  stated  above, 
viz.,  no  occluding  mate,  or  sixth  year  molar  root 
found  in  position  with  twelfth  year  molar  miss- 
ing. In  all  molar  cases  of  the  attachment  where 
it  does  not  become  necessary  to  impart  any  arti- 
ficial pressure,  a  simple  pin  attachment  is  all  that 
is  necessary."  The  washer,  B,  is  used  to  com- 
press the  spring  or  to  prevent  the  spring  from 
working  through  the  oblong  slot  in  saddle, 
through  which  the  T  head  of  stud  passes  in 
removing  and  replacing  the  case,  which  is  done 
daily  by  the  patient  wearing  the  case.  To  ad- 
just it  to  any  desired  pressure  against  the  ridge  the  adjusting  stud 
is  simply  rotated  one  way  or  the  other  until  the  desired  position 
is  secured.  The  key,  Fig.  672,  is  to  be  given  to  the  patient  for 
manipulating  adjusting  stud  at  will.  Dr.  W.  J.  Younger  of  Cali- 
fornia, who  has  had  personal  experience  with  this  form  of  denture, 
says  of  it :  "I  could  not  for  a  long  time  believe  it  was  of  such 
broad  and  universal  utility." 


Key  for  manipulating 
adjusting  stud. 


BRIDGE    DENTURES.  649 


METHODS  OF   CONSTRUCTING   CROWNS   AND   BRIDGES   IN    CASE 
OF    IRREGULARITY. 

A  young  lady  of  about  twenty-two  years  called  upon  the  writer 
for  services.  Her  mouth  presented  a  very  homely  appearance, 
which  was  largely  due  to  the  ignorance  or  lack  of  judgment  upon 
the  part  of  her  dentist  in  former  years.  The  history  of  her  case 
can  be  given  in  a  few  words.  It  is  a  characteristic  of  her  family  to 
have  large,  strong  teeth,  with  the  cuspids  quite  prominent;  but  in 
her  mouth  these  teeth  were  so  prominent  as  to  disfigure  her,  and 
when  she  commenced  to  grow  into  womanhood  her  mother  took 
her  to  their  dentist  to  have  the  irregularity  corrected.  This  gentle- 
man, as  I  have  said,  through  bad  judgment  extracted  the  two  lateral 
incisors,  and  allowed  the  cuspids  to   come   down   and   forward  to 

Fig.  673. 


partially  take  their  place.  Then  the  mischief  was  done.  The 
mouth  was  given  a  very  coarse  appearance  by  the  large  teeth  being 
brought  so  near  the  center,  and  as  they  did  not  entirely  fill  the 
space,  an  ugly  opening  was  left  between  these  teeth  and  the  central 
incisors.  (See  Fig.  673.)  When  the  lady  consulted  me,  it  was  with 
the  idea  of  having  the  cuspids  extracted  and  two  smaller  teeth 
inserted  upon  either  side;  it  was  her  wish  at  the  same  time  to  have 
it  done,  if  possible,  in  some  way,  so  that  she  would  not  have  to  wear  a 
plate.  After  studying  her  case  it  was,  therefore,  decided  to  extract, 
not  the  cuspids,  but  those  teeth  which  should  have  been  removed  in 
the  first  place — the  first  bicuspids.  Then  with  suitable  regulating 
appliances  the  angle  of  the  cuspids  was  corrected  and  they  were 
drawn  back  so  as  to  partially  fill  the  space  formerly  occupied  by  the 
first  bicuspids ;  at  the  same  time  the  second  bicuspids  were  brought 
into   line,   and  all   secured   with   retaining   appliances,   which   were 


650 


MECHANICAL   DENTISTRY. 


worn  for  several  weeks.  A  lateral  incisor  was  then  prepared  for 
either  side,  and  inserted  by  means  of  plate  and  pin  bridges. 
Described  by  Professor  Litch  on  page  565. 

The  result  obtained  was  exceedingly  gratifying,  a  fair  idea  of 
which  is  shown  in  Fig.  674. 

Another  case  is  one  treated  by  Dr.  I.  N.  Broomell,  who  con- 
tributes the  following  description : 

"  The  superior  cuspid  was  fully  Y\  of  an  inch  out  of  line ;  stand- 
ing inside  the  arch  to  such  a  degree  that  a  casual  glance  at  the  pa- 
tient would  lead  one  to  suppose  the  tooth  was  missing.  It  was 
also  imperfectly  developed,  so  that,  had  age  and  other  circum- 
stances favored  its  restoration  to  the  proper  position  in  the  arch, 
its  malformation  made  it  inadvisable  to  attempt  such  an  operation 
(Fig.  675).     The  patient  being  desirous  of  having  the  deformity 

Fig.  674. 


remedied,  at  least  so  far  as  appearances  were  concerned,  I  pro- 
ceeded to  do  so  in  the  following  manner :  Grinding  off  the  irregu- 
lar prominences  of  the  tooth,  I  made  it  more  perfectly  conical  in 
shape.  After  securing  an  impression  of  the  deformed  tooth  and 
casting  zinc  dies,  I  swaged  a  hollow  gold  cap  to  accurately  cover 
the  whole  surface  and  extend  slightly  under  the  gum.  This  added 
thickness  of  gold,  when  placed  over  the  tooth,  extended  the  labial 
surface  to  about  what  should  have  been  the  palatal  line ;  thus  per- 
mitting me  to  adjust,  by  grinding  and  filing,  a  porcelain  tooth  with 
its  backing  to  the  cap.  These  were  soldered  together  and  the  ap- 
pliance secured  on  the  cuspid  by  oxyphosphate  cement.  In  this 
case  no  pins  were  used,  the  cap  alone  being  sufficient  to  hold  the 
denture  in  position,  (a,  Fig.  675.)  It  has  now  been  in  the  mouth 
some  three  or  four  years,  during  which  time  I  have  removed  it 
several  times  in  order  to  be  satisfied  that  all  was  right  under  the 


BRIDGE   DENTURES. 


6« 


cap.  In  fact,  I  consider  that,  when  it*  is  at  all  possible  to  do  so,  all 
appliances  of  this  order,  including  small  pieces  of  bridge-work, 
should  be  so  constructed  that  they  may  be  removed  from  time  to 
time,  thus  affording  an  opportunity  to  detect  any  carious  condi- 
tions. 

"  Another  case  which  I  will  briefly  present  was  somewhat  similar 
in  construction  to  the  one  just  described,  but  was  inserted  under 
different  circumstances.  For  some  reason  unknown  to  the  patient, 
lie  had  lost  from  a  lower  incisor  the  entire  labial  surface,  extending 
from  the  cutting  edge  to  the  gum  margin,  and  somewhat  below  it. 
The  lingual  half  of  the  crown  remained,  and  fortunately  the  pulp 
was  not  exposed    (Fig.  676).     With  a  corundum  wheel  I  ground 


Fig.    675. 


Fig.    676. 


off  the  cutting  edge  of  the  tooth,  to  the  horizontal  dotted  line  seen 
in  the  illustration,  until  it  was  below  the  line  of  the  pins  in  the  porce- 
lain tooth,  which  had  been  selected  because  its  cross-pins  were  near 
its  cutting  edge,  and  ground  the  porcelain  tooth  to  fit  the  inclined 
surface  of  the  natural  organ.  I  then  fitted  a  backing  of  very  thin 
platinum,  allowing  it  to  extend  over  the  whole  back  of  the  porce- 
lain tooth,  including  the  inclined  surface.  After  making  a  cap  to 
perfectly  fit  the  lingual  surface  of  the  incisor,  I  pressed  it  around 
the  sides  until  it  could  be  soldered  to  the  backing,  thus  making  a 
cap  (a,  Fig.  676)  which  completely  covered  the  abraded  tooth,  oxy- 
phosphate  cement  being  used  in  setting  the  denture." 


65^ 


MECHANICAL   DENTISTRY 


BRIDGE-REPAIR. 

The  greatest  annoyance  which  bridge-work  is  likely  to  cause 
patient  or  operator  is  the  occasional  breaking  of  a  porcelain  facing. 
One  of  the  most  secure  and  artistic  methods  of  repairing  such  a 
break  is  that  devised  by  Dr.  E.  A.  Bryant,  and  is  illustrated  in  Figs. 
6yy,  678,  679,  and  680. 

His  method  is  as  follows :  Select  the  facing  to  be  attached, 
color,  size,  and  shape  to  suit,  grind  or  clip  off  the  pins  extending 
out  from  the  space  from  which  the  original  facing  was  broken  from 
the  bridge,  and  smooth  this  space  so  as  to  present  a  flat  surface. 
Drill  two  holes  through  the  backing  of  the  bridge  for  the  reception 
of  the  pins  of  the  new  facing  to  be  attached,  and  as  near  the  size 
of  the  pins  as  possible.  With  the  countersink  bur  in  the  right- 
angle  hand-piece,  countersink  from  the  inside  until  the  bur  comes 


Fig.    677. 


Fig.    678. 


Fig.    679. 


Fig.    680. 


through  to  the  front,  but  not  far  enough  to  enlarge  the  holes  (Fig. 
677 J.  Now  try  on  and  fit  the  facing,  grinding  the  backing  or  the 
tooth  to  accomplish  this  result.  When  fitted  to  suit,  cut  the  threads 
on  the  pins  of  the  facing  to  be  used,  first  with  the  larger  sized  die, 
then  with  the  smaller,  the  latter  being  the  perfect  thread  and  cor- 
responding to  the  nuts.  In  cutting  this  thread,  care  should  be 
taken  not  to  force  it  too  fast,  and  a  little  oil  should  be  used,  other- 
wise you  will  twist  off  the  pins  in  the  die,  and  it  is  difficult  to  re- 
move them,  besides  losing  the  use  of  the  facing. 

Now  select  two  nuts,  and  try  them  to  see  that  they  will  go  to 
place  on  the  pins  of  the  facing  before  putting  the  facing  in  place, 
laving  the  nuts  selected  in  such  position  that  you  will  be  able  to 
place  them  upon  the  same  pin  which  you  tried  them  on.  Place  the 
facing  in  position,  holding  same  close  and  tight  with  the  thumb  of 
the  left  hand,  pick  up  one  of  the  nuts  by  inserting  one  of  the  legs 


BRIDGE  DENTURES. 


653 


of  the  screw-driver  into  the  open- 
ing (Fig.  678),  carrying  the  nut 
to  the  pin  in  this  manner,   and 
starting  it  upon  the  thread,  then 
change  to  the  cut  in  the  nut  for 
the  reception  of  the  screw-driver, 
and  screw  to  place,  not  using  any 
force   to   do   so,    doing   likewise 
with  the  other  nut.     When  the 
two  are  in  place,  if  they  are  not 
quite     down,     hold    the     facing 
firmly    with    the    thumb    of    the 
left   hand,    then    screw    up   first 
one    nut,    then    the    other,    until 
entirely    home.     If    you    undertake    to 
screw  up  one  entirely  at  first,  and  there 
happens  to  be  the  least  tipping  upon  the 
other   side,    when   you   screw   the   other 
nut  down  tight  it  will  break  the  facing. 
Therefore    you    must    understand    it    is 
essential    to    screw    each    down    equally. 
Do  not  use  undue  force  with  the  screw- 
driver after  the  tooth  is  home,  with  the 
idea  of  making  it  extra  tight,  for  you  are 
liable  to  pull  the  pins  out  of  the  facing. 
The     strength     of     the     threads     being 
stronger  than  that  of  the  porcelain,  the 
latter  will  give  first. 

When  the  nuts  are  down  tight,  grind 
off  the  extending  parts  with  the  corun- 
dum wheel  and  smooth  up  with  cuttle- 
fish or  sandpaper  discs.  This  whole 
operation  consumes  about  fifteen  to 
twenty-five  minutes'  time.  With  these 
instruments  you  are  enabled  to  arrange 
new  facings  where  the  gum  happens  to 
have  receded,  or  where  they  encroach 
upon  the  gum.  By  baking  a  little  gum 
npon  the  facings  to  be  used,  you  can  fill 


Fig.  681. 


654  MECHANICAL   DENTISTRY. 

any  irregularities  at  the  junction  of  the  gum  and  facing,  thus  doings 
away  with  the  open  spaces  usually  seen  in  bridges  consisting  of  the 
six  anterior  teeth.  In  fact,  these  instruments  are  indispensable  to 
any  dentist  who  does  bridge-work  or  ever  contemplates  doing  it. 
They  can  be  used  to  great  advantage  in  many  other  operations  in 
dentistry,  covering  more  ground  than  any  other  set  of  instruments 
ever  devised  for  the  use  of  the  profession. 

If  the  pins  are  bent  and  the  nut  strikes  the  edge,  as  at  A,  Fig. 
679,  straighten  by  pulling  the  nut  and  pin  toward  the  side  it  does 
not  strike,  until  it  goes  home  (Fig.  680). 

When  it  is  found  necessary  for  any  reason  to  remove  a  crown 
or  bridge  from  the  mouth,  it  is  usually  desirable  to  do  so  with  as 
little  damage  to  the  fixture  as  possible.  The  old  method  of 
mutilating  the  bands  or  caps  with  burs  or  discs  is  now  unnecessary, 
since  we  have  in  the  "crown-slitter" — an  invention  of  Dr.  J.  B. 
Monfort — an  instrument  with  which  we  may  neatly  and  quickly  cut 
the  cap;  then  by  introducing  a  thin  chisel-shaped  instrument,  the 
edges  may  be  so  pried  apart  as  to  break  up  the  cement  and  readily 
admit  of  its  removal.  After  this  has  been  accomplished  and  the 
fixture  thoroughly  cleansed,  the  edges,  where  cut,  may  be  carefully 
brought  together  and  soldered,  so  as  to  admit  of  subsequent  re- 
placement. This  instrument  and  the  method  of  using  it  is  illus- 
trated in  Fig.  681. 


CHAPTER   XXXII. 

ELECTRICITY,  AND  ITS  APPLICATION  IN  DENTAL  MECHANICS. 

Historical. — Observations  of  electrical  phenomena  were  made 
at  a  very  early  date.  Thales,  one  of  the  seven  sages  of  Greece  (born 
640  b.  c.)  is  supposed  to  have  been  the  first  to  observe  that  amber, 
when  rubbed,  had  the  power  of  attracting  small  bodies.  The 
Greeks  knew  amber,  when  rubbed,  as  "  elektron,"  from  which  the 
word  "  electricity  "  has  been  derived.  These  ancient  people,  how- 
ever, had  but  little  knowledge  of  the  subject,  and  were  quite  unable 
to  explain  the  few  phenomena  they  observed. 

The  knowledge  of  electricity  remained  in  this  condition  for  about 
two  thousand  years,  when  William  Gilbert,  physician  to  Queen 
Elizabeth,  made  a  series  of  experiments  and  discoveries  in  electri- 
cal phenomena,  which  won  him  the  title  of  the  founder  of  the 
science.  "He  was  born  at  Colchester  in  1540,  studied  at  Oxford 
and  Cambridge,  afterward  establishing  himself  as  a  physician  in 
London,  where  he  died  in  1603.  Considering  the  period  in  which 
Gilbert  lived,  his  scientific  knowledge  must  have  been  remarkable. 
It  gained  for  him  the  favor  of  the  queen,  who  gave  him  the  means 
of  carrying  out  his  scientific  experiments,  and  also  appointed  him 
her  private  physician.  The  principles  and  theories  of  Lord  Bacon, 
who  frequented  Queen  Elizabeth's  court,  probably  greatly  in- 
fluenced Gilbert.  It  is,  however,  certain  that  he  did  not  adopt  the 
plan  previously  followed  by  schoolmen  of  making  daring  hypo- 
theses to  explain  natural  phenomena,  but  formed  his  ideas  from 
direct  experiment.  This  is  exactly  the  plan  adopted  by  Bacon. 
Gilbert  discovered  that  other  bodies  besides  amber  could  be  electri- 
fied by  friction.  He  also  ascertained  that  the  production  of  elec- 
tricity was  affected  by  moisture ;  that  hot  or  burning  bodies  lost  all 
electricity;  and  that  an  electrified  body  attracts  a  variety  of  other 
bodies,  whereas  a  magnet  only  attracts  steel  or  iron.  The  latter 
fact  shows  that  he  was  acquainted  with  the  difference  between  elec- 
tricity and  magnetism."  * 

*  "  Electricity,"  R.  Wormell. 
655 


656  MECHANICAL    DENTISTRY. 

Then  followed  (about  1670)  an  important  electrical  discovery  by 
Otto  von  Guericke.  Up  to  this  time  electricity  had  been  produced 
by  taking  larger  or  smaller  pieces  of  various  substances  in  one 
hand  and  rubbing  them  with  the  other.  This,  of  course,  produces 
very  small  quantities.  Guericke  now  added,  in  a  crude  form,  the 
electric  machine.  He  cast  a  globe  of  sulphur  and  supplied  it  with 
a  wooden  axle,  then  mounted  it  on  a  frame,  the  hand  being  employed 
as  the  rubber.  By  means  of  this  discovery  it  was  learned  that  the 
production  of  electricity  in  large  quantities  was  accompanied  by 
light  and  sound.  It  was  further  noticed  that  the  electrified  sulphur 
globe  attracted  light  bodies,  which  it  afterward  repelled,  until  they 
had  touched  some  other  body.  At  about  the  same  time  Picard  ob- 
served the  luminosity  of  greatly  rarefied  gases.  While  agitating 
the  mercury  in  an  imperfectly  exhausted  barometer  tube,  he  pro- 
duced electricity,  which  caused  the  mercurious  vapor  and  the  re- 
maining air  to  glow. 

Further  discoveries  were  made  by  Robert  Boyle  and  Dr.  Wall 
— the  former  discovered  that  substances  are  attracted  by  an  electri- 
fied body  in  a  vacuum,  while  the  latter  was  the  first  to  produce  the 
electric  spark. 

.Stephen  Gray,  a  Fellow  of  the  Royal  Society,  and  about  whom 
little  is  known,  discovered,  early  in  the  seventeenth  century,  that 
certain  bodies  were  capable  of  conveying,  or,  as  we  now  express  it, 
conducting,  electricity  from  one  body  to  another.  Contemporane- 
ously with  Gray,  Charles  F.  C.  DuFay,  of  the  Academy  of  Sciences, 
was  working,  in  France,  along  the  same  lines.  He  found  that 
electrified  bodies  attracted  the  unelectrified,  electrifying  them  in 
turn,  and  then  repelling  them.  He  also  discovered  the  insulating 
properties  of  glass. 

From  this  time  on,  through  the  seventeenth  century,  new  dis- 
coveries and  advances  were  made  in  electrical  science.  We  have 
the  work  of  Newton,  substituting  the  glass  ball  for  the  sulphur 
globe  employed  by  Guericke;  of  Gordon,  who  substituted  a  glass 
cylinder  for  Newton's  glass  ball ;  of  Morrison,  who  devised  and 
constructed  an  electric  telegraph ;  of  Kleist,  who  first  discov- 
ered the  means  of  accumulating  and  storing  up  large  quantities  of 
electricity.  This  discovery  was  also  independently  made  by  Mus- 
chenbroeck,  of  Leyden,  and  the  name  "  Leyden  jar,"  was  given  it. 
The  apparatus  was  soon  perfected,  receiving  its  present  form  of  a 


ELECTRICITY  :     ITS   APPLICATION    IN   DENTAL   MECHANICS.      657 

jar  coated  with  tin-foil,  inside  and  out,  at  the  hands  of  Sir  William 
Watson. 

One  of  the  greatest  names  in  the  early  development  of  electrical 
science  is  that  of  Dr.  Benjamin  Franklin,  of  Philadelphia.  His 
first  labors  (about  1750)  were  in  the  elucidation  of  the  theory  of 
positive  and  negative  electricity,  which,  however,  was  first  pro- 
pounded by  Sir  William  Watson. 

Franklin  claimed  that  electricity  was  not  created  by  friction,  but 
was  only  transferred  from  one  body  to  another.  That  is,  "  a  body 
which  becomes  positively  electrified  receives  its  charge  of  electri- 
city from  one  or  more  other  bodies  which  will  be  found  to  be  neg- 
atively electrified.  In  other  words,  positive  electrification  is  due  to 
an  excess  of  electricity,  and  negative  electrification  to  a  deficiency." 
Franklin  also  set  forth  the  analogies  between  lightning  and  the 
electric  spark,  and  in  some  of  his  earliest  writings  he  enumerates 
the  electrical  effects  which  were  manifested  by  lightning.  His  later 
experiments  with  his  kite  and  iron  key  are  a  matter  of  familiar 
history.  A  few  years  later  (1759)  Robert  Symmer  advanced  the 
idea,  in  opposition  to  Franklin's  theory,  that  there  were  two  kinds 
of  electricity,  not,  however,  independent  of  each  other,  but  coex- 
istent. 

Then  followed,  at  the  close  of  the  eighteenth  century,  many 
interesting  experiments  by  Coulomb,  Galvani,  and  Volta.  The 
new  century  opened  with  the  accumulated  evidence  of  the  past, 
and  soon  presented  Sir  Humphrey  Davy,  Oersted,  Ampere, 
Seebeck,  and  Faraday.  Davy  was  the  first  to  offer  an  explanation 
of  the  chemical  action  of  the  electric  current  in  decomposing  water, 
and  in  18 10  he  produced  the  arc  light  for  the  first  time,  at  the  Royal 
Institution.  He  used  carbon  points  as  his  electrodes,  and  a  bat- 
tery, it  is  said,  of  2000  cells. 

The  discovery  of  the  connecting  link  between  the  phenomena  of 
electricity  and  magnetism  was  made  by  Oersted,  of  Copenhagen, 
who,  in  1820,  observed  that  a  current  of  electricity  flowing  along 
a  conductor  deflected  a  magnetic  needle  placed  near  it,  and  his  ex- 
periments were  eagerly  followed  by  Ampere,  in  France,  who  built 
up  a  wonderful  mathematical  theory  of  the  magnetic  action  of  linear 
conductors  carrying  currents.  Seebeck,  in  1822,  opened  up  a  most 
interesting  department  of  electricity  by  the  discovery  of  a  method 
of  converting  heat  energy  into  electrical  energy,  and  he  founded 
42 


658  MECHANICAL   DENTISTRY. 

the  science  of  thermo-electricity.  The  last  of  this  group  is 
Michael  Faraday,  the  pupil  of  Sir  Humphrey  Davy,  and  we  owe 
to  him  the  further  working  out  of  many  of  Davy's  ideas.  Fara- 
day's name  is  chiefly  associated  with  the  laws  of  electrostatics  and 
magneto-electric  induction.  The  great  importance  of  this  discov- 
ery of  induction  may  be  seen  by  looking  to  the  present  condition 
of  electro-technics — the  telegraph,  telephone,  dynamo  machine,  etc. 
Faraday  also  substituted  electrode  for  pole,  calling  the  positive  elec- 
trode the  anode,  and  the  negative  the  cathode. 

From  the  period  of  Davy  and  Faraday  on  to  the  present  time 
may  be  considered  modern  history  in  electric  science,  and  among  the 
names  most  cherished  in  this  domain  are  Samuel  Morse,  Alexander 
Bell,  Thomas  Edison,  Elihu  Thompson,  and  Sir  William  Thomp- 
son, Cyrus  W.  Field,  Edwin  J.  Houston,  and  Nikola  Tesla. 
While  we  must  not  forget  to  do  honor  to  the  earliest  investigators 
— as  their  labors  helped  to  bring  the  science  to  its  present  posi- 
tion— yet  the  discoveries  and  developments  which  have  been  and 
are  being  made  by  our  present  brilliant  scientists,  are,  in  the  closing 
years  of  the  nineteenth  century,  resulting  in  a  great  social  revolu- 
tion. Electricity  is  now  used  and  depended  upon  in  countless  de- 
partments of  science,  and  in  the  arts  of  peace  and  war;  in  fact,  no 
other  element  ministering  to  the  good  of  mankind  has  ever  proved 
such  a  versatile  servant. 

Electric  Energy. — The  fundamental  principle  with  which  we 
have  to  deal — though  it  was  not  so  accepted  by  physicists  until  the 
middle  of  the  nineteenth  century — is  the  conservation  of  energy. 
For  the  study  of  dynamics,  we  learn  that  an  agent  that  is  capable 
of  doing  work  possesses  a  certain  amount  of  energy,  and  it  is  only 
due  to,  and  so  far  as  it  possesses,  this  energy  that  it  is  capable  of 
doing  work.  Examples  of  what  is  known  as  actual  energy  are  the 
energy  of  sensible  motion,  as  in  a  cannon  ball,  of  sound-waves,  of 
heat,  etc. ;  of  potential  energy,  that  of  position  of  a  weight  raised 
above  the  earth,  of  elasticity  in  a  bent  bow ;  of  electricity,,  chemical 
combination,  etc.  Potential  or  positional  energy  and  actual  energy 
are  in  incessant  interconversion ;  for  potential  energy  implies  force, 
or  a  tendency  to  motion,  as  much  as  actual  energy  implies  motion 
or  change  of  position. 

From  the  above  we  learn  that  electricity  in  motion,  or  the  electric 
current,  is  a  form  of  energy.     And  this  can  only  be  procured  by 


ELECTRICITY  :     ITS   APPLICATION    IN   DENTAL   MECHANICS.      659 

the  continuous  expenditure  of  energy — as  through  the  steam-engine 
and  dynamo,  for  instance — while  through  or  from  electricity  in 
motion  various  forms  of  energy  can  be  procured,  as  in  heat, 
light,  and  power.  Thus,  we  observe  the  wonderful  correlation  of 
energies  or  forces ;  that  is,  the  transformability  of  one  form  into 
another. 

Electrical  Terms. — Before  going  further  into  the  subject,  the 
student  should  fix  in  his  mind  a  few  of  the  most  important  terms 
adopted  for  designating  certain  principles  in  the  management  and 
application  of  the  electric  current.  The  ampere  is  the  unit  of  current 
strength ;  that  is,  it  is  the  flow  produced  by  the  pressure  of  one 
volt  in  a  circuit  whose  resistance  is  one  ohm.  An  anode  is  the 
positive  terminal  or  electrode,  cathode  being  the  name  given  to  the 
negative  terminal.  The  ohm  is  the  unit  of  electrical  resistance.  A 
rheostat  is  an  apparatus  for  throwing  a  variable  resistance,  or  num- 
ber of  ohms,  into  a  circuit  at  will.  The  volt  is  the  unit  of  electro- 
motive force  or  pressure,  while  a  watt  is  the  unit  of  activity  or  rate 
of  doing  work.  The  activity  of  a  circuit  expressed  in  watts  is  the 
product  of  the  volts  multiplied  by  the  amperes.  Seven  hundred  and 
forty-six  watts  represent  one  horse-power. 

Electric  Dental  Apparatus. — The  advent  of  the  incandescent 
lamp,  in  1880,  made  electricity  in  dentistry  practicable;  it  brought 
with  it  other  benefits,  besides  the  convenience  and  superiority  of  the 
light  in  the  office  and  laboratory.  It  solved  the  problem  of  supply, 
and  has  done  as  much  as  any  other  agent  to  place  the  practice  of 
dentistry  upon  its  present  advanced  plane,  and  through  it  the  dentist 
has  the  power  to  do  more  work,  and  to  do  it  more  conveniently,  and 
with  less  discomfort  and  fatigue  to  himself  and  clients. 

The  principal  electric  dental  apparatus  may  be  summarized  as  the 
motor  for  running  the  laboratory  lathe  and  office  engine,  the  mouth 
lamp,  root-dryer,  hot-water  heater,  gold  annealer,  apparatus  for 
producing  cataphoresis,  the  electric  oven  or  furnace  for  porcelain 
crown-  and  bridge-work,  etc. 

The  Electric  Motor. — An  electric  motor  may  be  defined  as  a 
machine  for  converting  the  energy  of  an  electric  current  into  me- 
chanical energy.  These  are  manufactured  in  various  forms  and 
sizes  according  to  the  amount  and  form  of  energy  required. 

Electric  Engine. — The  most  useful  of  all  the  electric  dental  ap- 
paratus is  the  motor-driven  engine  and  lathe.     A  simple  form  of 


66o 


MECHANICAL   DENTISTRY. 


motor  for  this  purpose  is  shown  in  Fig.  682.     The  electro-dental 
engine  should  be  as  simple  and  light  as  possible,  thus  reducing  the 


Fig.  68; 


moving  parts  to  a  minimum,  making  the  bearings  few  and  easily 
accessible.     The  motor  also  should  be  carefully  mounted,  so  as  to 


electricity:    its  application  in  dental  mechanics.     66i 

minimize  the  vibrations.  If  it  is  fastened  to  the  floor  or  a  wooden 
stand  it  is  advisable  to  insert  a  felt  or  rubber  pad  between  the  feet 
of  the  motor  and  the  woodwork.  Electric  motors  are  supplied  with 
rheostats,  through  which  the  power  is  controlled.  For  dental  pur- 
poses these  are  made  so  as  to  be  controlled  by  the  foot  of  the 
operator.  The  later  forms  of  these  devices  are  so  arranged  that  the 
dental  engine  can  be  stopped,  started,  or  reversed  instantly.  They 
also  give  the  operator  the  advantage  of  half  a  dozen  different  speeds. 

The  apparatus  represented  in  Fig.  682  consists  of  the  S.  S.  White 
dental  motor  No.  2,  an  iron  stand  with  a  mahogany  top,  on  which 
it  sits,  a  fire-proof  speed-regulating  resistance  in  an  iron  case  sup- 
ported by  the  stand,  an  electromagnetic  clutch  on  a  countershaft 
supported  on  front  of  stand,  and  a  governing  treadle,  or  rheostat, 
connected  to  it  by  a  cable.  The  motor  is  inclosed  in  a  glass  vase 
to  protect  it  from  dust,  and  the  stand  is  mounted  upon  rubber 
rimmed  wheels  to  facilitate  its  movement  from  one  position  to 
another.  The  several  speeds  given  to  the  engine-bit  through  this 
apparatus  may  vary  from  500  to  5000  revolutions  per  minute.  The 
entire  control  of  the  running  of  the  engine  is  in  the  treadle,  as 
previously  explained. 

Laboratory  Lathe. — AVhen  the  motor  is  employed  for  driving  a 
laboratory  lathe  a  different  form  of  rheostat  is  used,  as  it  is  not 
necessary  to  have  this  machine  so  thoroughly  under  control.  A 
rheostat  and  motor  similar  to  those  shown  in  Fig.  683  are -generally 
employed. 

The  motor  shown  at  a,  is  of  about  ]/%  horse-power,  which,  with 
the  1 10- volt  incandescent  current,  will  run  a  dental  lathe  with  more 
satisfaction  than  any  other  power  at  present  known  to  us.  The 
rheostat  (b)  is  so  arranged  that  the  different  speeds  can  be  governed 
by  the  slight  raising  or  lowering  of  the  foot-pedal.  The  wires  at- 
tached to  the  binding  posts,  a,  b,  are  for  connection  with  the  in- 
candescent current. 

The  Electric  Oven  or  Furnace. — The  utility  of  the  electric 
furnace  depends  upon  the  fact  that  the  electric  current  can  convey 
energy  from  the  outside  into  a  closed  space,  and  liberate  it  there  in 
the  form  of  heat.  The  electric  furnace  is  available,  not  only  for 
metallurgical  operations,  but  for  some  of  the  finest  of  the  dental 
laboratory  procedures,  as  well  as  for  chemical  experiments. 

A  very  complete  furnace  for  metallurgical  purposes  in  which  the 


662 


MECHANICAL    DENTISTRY. 


electric  arc  is  produced  is  shown  in  Fig.  684.*  Ordinary  electric 
light  carbons,  c  c',  slide  through  the  clamping  cylinders  p  p',  and 
are  brought  together  just  over  the  crucible  cr,  at  right  angles  to 
one  another.  For  many  reasons  this  position  is  found  to  be,  for 
general  work,  more  convenient  than  the  vertical   position  used  in 


Fig.  683. 


the  Siemens  furnace.  The  crucible,  according  to  the  operation 
that  has  to  be  performed,  consists  of  carbon,  plumbago,  lime,  mag- 
nesia, etc.  It  is  in  a  closed  refractory  chamber  k,  with  an  aperture 
Bo  at  the  top  through  which  the  materials  to  be  smelted  can  be 
introduced.     When  large  currents  are  used,  the  carbon  holders  p  p' 


*  Described  by  Professor  R.  M.  Wamsley,  Edinburgh. 


ELECTRICITY  :     ITS   APPLICATION    IN   DENTAL   MECHANICS. 


663 


have  to  be  kept  cool  by  currents  of  water  circulating  through  them. 
The  front  side  of  the  furnace  chamber  is  closed  by  the  removable 
screen  k,  which  for  many  purposes  can  be  made  of  deep  ruby-red 
glass,  through  which  the  operations  in  the  crucible  can  be  watched; 
but  when  the  highest  temperatures  are  developed  it  has  to  be  made 
of  a  more  refractory  material.  There  are  apertures  not  shown  in 
the  figure,  by  which,  if  required,  gases  can  be  introduced  into  the 
furnace.     The  magnet  a1  controls  the  play  of  the  electric  arc  on 


Fig.  684. 


the  materials  in  the  crucible,  converting  the  arc,  if  need  be,  into  a 
long  flame  which  acts  as  a  veritable  electric  blowpipe.  The  maxi- 
mum temperature  attainable  is  about  63320  F.,  the  temperature, 
according  to  M.  Violle,  at  which  carbon  volatilizes.  With  a  current 
of  about  12  amperes  at  55  volts  the  most  refractory  ores  can  be 
reduced  in  a  few  minutes,  and  pure  metals  can  be  obtained  in  suffi- 
cient quantities  for  chemical  analysis.  In  this  way,  at  the  Ecole 
Normale  Superieure,  specimens  of  metallic  ruthenium  and  osmium 
have  been  obtained. 


664  MECHANICAL    DENTISTRY. 

The  writer  has  had  a  more  simple  device  constructed  for  experi- 
mental metallurgical  work  at  the  Pennsylvania  College  of  Dental 
Surgery,  consisting  of  a  carbon  crucible  for  the  cathode  and  a  car- 
bon point  for  the  anode.  The  carbon  crucible  is  constructed  so 
as  to  act  both  as  a  crucible  in  which  metal  may  be  fused  and  as 
a  conductor  for  the  current  employed  for  that  purpose.  The 
carbon  pencil  has  a  small  screw  attachment  at  the  upper  end  for 
the  connection  of  the  positive  wire,  while  a  similar  screw,  con- 
nected with  the  crucible,  is  for  the  negative  wire.  After  the  current 
has  been  turned  on,  the  point  of  the  pencil  is  carefully  brought  in 
contact  with  the  bottom  of  the  crucible,  or  the  metal  which  it  may 
contain,  thus  establishing  the  current.  After  this  is  done  the 
pencil  may  be  slowly  withdrawn  two  or  three  inches  from  the 
metal,  which  will  form  an  electric  or  voltaic  arc.  The  heat  of  the 
voltaic  arc  is  intense,  and  hence  can  be  employed  for  fusing  the 
most  refractory  substances.  Platinum,  for  instance,  can  be  brought 
to  the  molten  condition  in  a  few  seconds. 

The  electric  oven  for  fusing  porcelain  in  crown-,  bridge-,  and  con- 
tinuous-gum-work is  quite  a  different  and  more  recent  apparatus. 
In  1890  Mr.  J.  O'Meara  devised  an  electric  heater,  consisting  of  a 
muffle  of  fire-clay,  with  wires  imbedded  in  the  same,  and  patented 
the  combination  of  a  furnace  with  a  rheostat.  This  patent  was  pur- 
chased by  Dr.  H.  C.  McBrair,  and  is  incorporated  in  what  is  now 
known  as  the  "  McBrair  furnace,"  evidently  the  first  to  be  devised 
and  employed  for  fusing  porcelain,  and  is  very  complete  and  satis- 
factory for  dental  laboratory  work.  This  furnace  is  shown,  with 
the  rheostat  to  control  the  current,  in  Fig.  685.  The  electric  furnace 
has  several  advantages  over  every  other  form  of  apparatus  for  sim- 
ilar purposes : 

First. — The  heat,  not  being  the  direct  product  of  combustion,  is 
pure,  and  is  radiated  equally  from  all  directions  within  the  oven; 
and  what  is  known  in  porcelain  work  as  "  gassing  "  is  therefore  an 
impossibility.  The  ease  and  accuracy  with  which  this  heat  can  be 
secured  and  controlled  is  also  a  great  desideratum. 

Second. — The  piece  to  be  fused  can  be  placed  in  the  oven  with- 
out previous  heating,  and  remain  there  after  fusing  until  entirely 
cool.  That  is,  the  invested  piece  may  be  placed  in  the  oven,  the 
lid  closed,  and  current  turned  on  gradually  by  the  rheostat,  and 
when  properly  fused  the  button  is  turned  and  the  work  done. 


ELECTRICITY  :     ITS   APPLICATION    IN    DENTAL   MECHANICS.       665 

Third. — The  oven  is  small,  clean,  and  noiseless,  and  can  therefore 
be  used  as  conveniently  in  the  office  as  in  the  laboratory. 

Fourth. — The  cost  of  operating,  compared  with  other  methods, 
is  reduced  to  a  minimum. 

Minor  Apparatus.- — The  motors  usually  employed  in  the  dental 
office  are  furnished  with  an  extra  pair  of  brushes   and  collecting 

Fig.  685. 


rings,  and  supply  an  alternating  current,  which  is  sent  through  a 
transformer,  where,  by  induction,  it  generates  a  secondary  current 
to  operate  the  smaller  apparatus,  such  as  the  electric  mallet,  mouth 
lamp,  hot-air  syringe,  cautery,  etc.  These  appliances,  however,  can 
be  operated  quite  as  satisfactorily  from  an  electric  battery. 

The  Electric  Mallet. — This  piece  of  apparatus  combines  the 
work  of  Drs.  Bonwill  and  Webb  in  this  direction.  It  has  favor 
with  many  of  the  most  skilful  operators  in  the  world,  and  by  some 


666 


MECHANICAL    DENTISTRY. 


Fig.  686. 


is  thought  to  approach  more 
nearly  to  the  ideal  condensing 
instrument  than  any  other  ever 
offered  to  the  profession.  This 
instrument  is  illustrated  in  Fig. 
686. 

A  later  form  of  electric  dental 
mallet   is   that   designed   by   Dr. 
Perry  Skinner,  and  shown  in  Fig. 
687.     In  this  instrument  there  is 
no    friction   connected   with    the 
armature,    as    it    stands    directly 
over     its     field     of     magnetism, 
guided  by  the  tool  holder  passing 
through    its    center    to    a    point 
where  it  strikes  the  tool.    Owing 
to   this   arrangement,   as    free   a 
blow  is  struck  as  that  given  by 
a    hand    mallet.     Previously    all 
mallets  of  sufficient  power  were  made  with  two 
or   more   magnets,    but   by    using   a   magnet    of 
special  design  one  is  found  to  meet  all  require- 
ments, and  to  condense  gold  thoroughly.     This 
mallet  works  by  pressure  on  the  point  or  side 
of  point,  thereby  removing  all  complicated  slid- 
ing connections  from  the  hand-piece  of  the  in- 
strument.    It  also  enables  the  operator  to  have 
free  access  to  the  electric  contacts  at  the  other 
extremity.     Owing  to  the  simplicity  of  construc- 
tion and  arrangement  of  these  contacts  they  can 
be  removed  and  replaced  by  any  person  having 
a  limited  knowledge  of  electricity.     This  mallet 
also  has  a  specially  designed  connection  (a)  for 
the  electric  cable,  which  gives  the  instrument  a 
perfectly  free  motion.     The  adjustment  regulat- 
ing the  blow  is  very  simple  and  under  the  control 
of  the  operator. 

Electric  Mouth  Lamp. — With   this  miniature 
electric  lamp  (shown  in  Fig.  688)  the  dentist  has 


ELECTRICITY  I     ITS   APPLICATION    IN   DENTAL    MECHANICS.      667 

a  means  for  exact  diagnosis  in  certain  pathological  conditions  of 
the  teeth,  which,  with  ordinary  means,  are  difficult  to  locate.  It 
lights  up  the  mouth  so  effectively  that  a  hidden  cavity  of  decay, 


Fig.  687. 


Fig.  688. 


:» 


■an  unsuspected  devitalized  pulp,  or  any  deviation  from  normality 
in  the  body  of  the  teeth  will  be  readily  discernible.  With  the 
electric  lamp  placed  back  of  the  teeth,  those  that  are  sound  will 
appear  translucent,  without  variations  in  structure,  while  a  devital- 


668  MECHANICAL    DENTISTRY. 

ized  tooth  will  appear  opaque,  even  when  to  ordinary  observation 
its  color  gives  no  such  indication. 

Electric  Hot-air  Syringe. — The  value  of  the  hot-air  blast  in 
dental  operations  is  recognized  by  all  intelligent  operators,  and 
when  the  manufacturers  produced  an  apparatus  for  generating  this 
through  the  agency  of  the  electric  current,  they  gave  us  a  neat, 
convenient,  and  time-saving  instrument.  The  appearance  of  the 
appliance  can  be  seen  by  referring  to  Fig.  689. 

A  switch  under  the  thumb  makes  the  circuit  and  gives  the  dentist,, 
on  compressing  the  rubber  bulb,  an  instant  current  of  heated  air, 
which  can  be  regulated  from  slightly  warm  to  the  hottest  blast. 

Different  sized  nozzles  can  be  screwed  on,  giving  fine  or  diffused 
jets  of  air;  and  as  glass  is  a  poor  conductor  of  heat,  the  handle 
remains  cool  while  the  air  loses  none  of  its  heat. 

Fig.  689. 


Cataphoric  Apparatus. — The  medication  of  tooth  structure  by 
electric  osmosis,  or,  as  it  is  generally  known,  "  cataphoresis,"  has 
taken  a  very  important  place  in  dental  therapeutics,  and  we  believe, 
that  in  the  hands  of  intelligent  and  careful  operators  it  will  prove 
one  of  the  most  important  discoveries  ever  made  in  the  field  of 
dental  science.  We  say  in  the  hands  of  "  intelligent  and  careful 
operators  "  for  the  reason  that  to  practise  it  intelligently  requires 
as  great  a  breadth  of  knowledge  as  any  other  process  in  dental  or 
medical  practice.  It  requires  a  knowledge  of  the  principles  under 
which  electricity  operates,  and  the  conditions  necessary  for  its  suc- 
cessful application ;  a  knowledge  of  the  control  of  the  agent,  of 
resistance,  and  of  electrolysis. 

Through  the  employment  of  electric  osmosis,  the  most  sensitive 


ELECTRICITY  :     ITS   APPLICATION    IN    DENTAL    MECHANICS.      669 


Fig.  690. 


dentine  may  be  obtunded,  living  pulps  be  painlessly  removed,  or 
discolored  teeth  may  be  readily  bleached.  Numerous  forms  of 
apparatus  have  been  devised  for  the  application  of  this  process, 
which  have  proven  more  or  less  successful.  It  will  answer  our 
purpose  here,  however,  to  illustrate  two  of  the  most  simple  and 
effective,  yet  offered  to  the  profession.  Fig.  690  shows  an  excellent 
instrument  for  the  utilization  of  the  street  current. 

The  resistance  board   (A)   is  hung  on  the  wall,  in  a  convenient 
position  for  operating — the  controller   (B) 
being  placed   either   on  the  office  bracket, 
or,  if  preferred,  in  the  patient's  lap,  and  can 
be  operated  by  either  party.     By  pushing 
the  lever  forward  on  the  resistance  board 
to   point   of   first   contact,   seven   volts   are 
conducted    to    the    controller — by    turning 
handle   (D)   you  increase  the  voltage  from 
nothing  to  a  maximum  of  seven  volts  by 
gradations    of    one    to    ten    volts.     Should 
stronger    current   be    required,    the    handle 
on   controller   must   first  be   brought   back 
to  zero;  the  lever   (C)   can  then  be  pushed 
forward  to  point  of  second  contact,  when 
12    volts    will    be   conducted    to   controller, 
and  so  on  to 
30  volts.   The 
simple   move- 
ment of  han- 
dle   (D)    will 
then     be     all 
that  is  neces- 
sary. 

The  Dry  Cell  Battery  System. — In  the  next  illustration,  Fig. 
691,  is  shown  the  ideal  instrument  for  the  employment  of  the  battery 
system.  Some  of  the  advantages  of  this  apparatus  are  compact- 
ness, cleanliness,  constancy  of  current,  and  durability ;  the  weight  of 
each  cell,  too,  being  only  about  two  ounces,  25  or  50  of  them,  with 
the  case,  meter,  current  controller,  electrodes,  etc.,  make  it  perfectlv 
portable.  These  cells  being  hermetically  sealed  admit  of  no  leak- 
age; and  should  one  of  the  batteries  be  tipped  over,   an  accident 


6jo 


MECHANICAL   DENTISTRY. 


likely  to  happen  to  any  instrument  of  the  kind,  it  can  remain  in  a 
reversed  position  for  an  indefinite  period  of  time  without  being 
injured  in  the  slightest.  Then,  again,  as  caustic  and  corrosive 
liquids  do  not  enter  into  the  composition  of  the  cells,  the  batteries 
remain  clean  at  all  times,  and  connections  cannot  become  corroded 
so  as  to  interfere  with  the  circuit.  The  simplicity  of  mechanism 
and  absence  of  parts  likely  to  wear  prevents  any  necessity  for 
repairs,  so  that  the  life  of  this  battery  is  only  limited  by  the  actual 
amount  of  work  done.     The  strength  of  the  chlorid  of  silver  cell  is 


Fig.  691. 


fixed  and  constant,  each  cell  representing  one  volt.  They  are  also 
very  readily  removed,  so  that  any  one  can  readily  fit  out  a  50-cell 
battery  with  an  entire  new  set  of  cells,  or  replace  any  one  cell  in 
a  series  with  a  fresh  one  in  a  few  minutes  without  disturbing  the 
balance.  Other  features  of  this  outfit  are  its  meter  for  measuring 
the  current  and  the  rheostat  for  controlling  the  same.  The  latter 
permits  of  administering  the  current  smoothly  and  with  the  greatest 
minuteness  of  dosage.  With  these  two  adjuncts  the  current  is 
manipulated  to  a  nicety,  the  patient  not  being  used  as  a  meter,  as 
is  too  often  the  case. 


INDEX. 


ADJUSTING  clasps  to  the  plate,  192 
Air-chambers,   151,  199,  200 
All-gold  crown  or  cap,  artificial,   537 
Alloys,    aluminium,    109 

bismuth,    116 

compounding,    117 

copper,    in 

fusible,    175 

general    properties    of,    117 

gold,   determining  the  carat  of,   85 
formulas  for,  81 
reducing,  to  required  carat,  80 

platinum,    105 

silver,  98 

tin,    115 
Aluminium,    107 

alloys    of,    109 

annealing,    108 

casting,    109 

corrodibility   of,    108 

dental  uses   of,    no 

derivation   of,    107 

fusing-point    of,     108 

general   properties    of,    107 

melting,    manner    of,    109 

polishing,    109 

soldering,    109 

solubility  of,    108 
Antagonizing  dentures,  206,  238,   242 

models,  manner  of  securing,  203 
Anthracite  coal  as  a  fuel,   26 
Antimony,    115 

fusing-point    of,    115 

general   properties   of,    115 
Appliances  for  the  correction  of  dental 
irregularities,    434 

for     the     correction     of     fractured 
maxilla?,    400 

used  in  the  generation  and  applica- 
tion of  heat,  31 
Arranging  teeth,  220,  228,  249,  284 
for   temporary   plates,    248 
Articulators,    243 

Artificial   all-gold   crown   or  cap,    537 
repairing,     549 

crown,  Bonwill's,  487 
Brown's,  448 
devitalization  of  pulp   for,   477 


Artificial  crown,  excision  of  vital  tooth- 
pulp  in  preparation   for,  477 
Foster's,    495 
Gates',   494 

gold    seamless    contour,    542 
Howland's,    496 
introductory    remarks    on,    474 
Logan's,  479 

porcelain,   with  gold  collar  at- 
tachment, 496 
dovetail,   493 
Baldwin's       method       for 

making,    498 
Kirk's    method    for    mak- 
ing,  498 
Shulze's  method  for  mak- 
ing,   502 
Stowell's        method        for 
making,    500 
preparation    of  pulp  canal   for, 
478 

of  the  root  for,  476 
Richmond's,  new,  485 
dentures,  beaded  or  grooved,  325 
continuous-gum,    264 
entire,    213 

on    celluloid    base,    327 
rubber  base,  281 
partial,   constructed  on   a  base 
of  rubber,  317 

retained   in   the   mouth   by 

means    of  clasps,    178 
supported    by    atmospheric 
pressure      or      adhesion, 
198 
treatment    of    the    mouth    pre- 
paratory to  the  insertion  of, 
120 
ferrule    or    collar    crown,    Knapp's 
process  for  making,   520 

as  applied  to  bicuspid 

roots,    510 
Litch's      method      for 

making,    5 1 3 
Mason's     method     for 

making.    535 
Richmond's        method 
for    making,    503 


671 


672 


INDEX. 


Artificial      ferrule      or      collar      crown, 
Shield's   method    for   making,    526 
palates,    376 

for  congenital  fissure,  382 
method  of  making,   385-399 
Asbestos  molds,  90 

Atmospheric  pressure  or  adhesion,   198, 
213,    214,    215 


BABBITT  metal,  112,  174 

Backing  the  teeth,  manner  of,  208,  256 

Baker's   velum,    396 

Baking    furnaces,    51 

Basal   temperaments   and  their   general 

indications,  225,  226 
Beaded  or  grooved  dentures,   325 
Beeswax  as  an  impression  material,  129 
Bellows   blowpipe,    37 
Bismuth,    116 

alloys  of,    116 
fusing-point    of,    116 
general  properties   of,   116 
Bite,  manner  of  taking  the,  202 
Bituminous   coal  as  a   fuel,  24 
Blowpipes,   34 
bellows,    37 
gasolene,   42 
mouth,  34 
oxycarbon,    42 
oxyhydrogen,    44 
Bonwill's    articulator,    243 
Brass  solder,   112 
Bridge    dentures,    552 

in    case    of   irregularity,    649 
limitations    of,    553 
removable,    621 

Carr's  method  of  making, 

644 
Condit's    method    of    mak- 
ing,   638 
Davenport's      method      of 

making,    629 
Parr's  method  of  making, 

626 
Mandrel    system    of    mak- 
ing,  633 
stationary,    553 

Darby's    method    of    mak- 
ing,   564 
Knapp's    method    of    mak- 
ing.   587 
Litch's    method    of    mak- 
ing,  565 
Low's   method   of  making, 

589 

Melotte's  method  of  mak- 
ing.   593 

T'armly  Brown's  method 
of  making,  618 


Bridge    dentures,    stationary,    Register's 
method  of  making,  575 

Webb's  method  of  making, 

554 
Williams'  method  of  mak- 
ing,  576 
Hollingsworth's  system  of 

making,    609 
Mandrel    system    of    mak- 
ing,   596 
Brown's  clamp  flask,  297 
Burners,    32 


CARBON   molds,   91 
Cast  base,  gold  alloy,  365 
metal,   362 

repairing,   371 
Casting    aluminium,    109 
Cataphoric    apparatus,    668 
Celluloid,   327 

as    a    base    for    artificial    dentures, 

327 
attachment   for   metallic   base,    354 
composition    and    manufacture    of, 

328 
finishing,    349 
hot  moist-air  machine  for  molding, 

337 
investing,    331 
metal  casts  for,   330 
modeling,   337 
molding,   by    dry   heat,    343 

in   steam,   340 
plaster  model   in  molding,   329 
processes    preliminary    to    molding, 

329 
selection  and  preparation  of,  334 
vulcanite    faced  with,    349 
waxing   or   modeling,    331 
zylonite    compared   with,    353 

Charcoal  as  a  fuel,  23 
molds,   90 

Clasps,    adjusting,    to    plate,    193 

metallic,    attached   to  rubber   plate, 

318 
modifications  in  form  of,   183 
observations   on  use   of,    178 
partial   or   stay,    186 
scalloped,    186 
securing,   to   plate,    193 
separation  of  teeth  for,  182 
standard,    185 

teeth   for  application   of,   180 
with    spurs,    196 

Coal  as  a  fuel,  anthracite,  26 
bituminous,    24 

Coke  as  a  fuel,   24 

Components   of   dental   norcelain,   258 

Composition   and  manufacture  of  cellu- 
loid,   328 


INDEX. 


6/3 


Compounding  and  general  properties  of 
alloys,    117 

rubber   for   dental   purposes,   282 
Constructing       and       attaching       spiral 

springs,  252 
"  Continuous-gum "     dentures,     264 

Allen's     methods     of     making, 

266 
Haskell's    methods    of   making, 

Tees'  methods   of  making,  276 
Converting  gold  alloys  into  the  required 

forms,    89 
Copper,    in 

alloy,  Babbitt  metal  as  a,   112 

German   silver  as   a,    112 
alloys  of,   in 
general  properties   of,    in 
Correction      of      dental      irregularities, 

appliances  for  the,  434 
Corrodibility   of   aluminium,    108 
Counter-dies,    156,    168 

progressive,    169 
Crowns,    artificial,    474 
Crucibles,  65 


DEFECTS  of  the  palatal  organs,  373 

artificial    palates    for,    376 
for        congenital, 

382 
method    of    mak- 
ing,   385 
Baker's   velum    for,    396 
Kingsley's    appliance    and 
methods     of     procedure 
for,    375 
Suersen's     appliance     for, 
392 
Dental  irregularities,  appliances  for  the 
correction  of,  434 

Case's  methods  of  treating,  458 
contraction  of  the  arch  in,  440 
lack    of    anterior    occlusion    in,  . 

45i 
mechanical    forces    in.    434 
method  of  retraction  in,  448 
misplaced    bicuspids    in,    440 
most  frequent  forms  of,  434 
protruding    apparatus    for    cor- 
recting.   462 
cuspids    in,    435 
protrusion    of    lower    jaw    in, 
448 

of  upper  jaw  in.  444 
regulating,      supplemented      by 

crown-work,    _i."4 
re-nosing  the   features   in,   456 
retruding    apparatus    for    cor- 
recting,   s6i 

cuspids    in.    438 

43 


Dental  irregularities,  rotation  by  rubber 
rings  in,  450 

by  spring  bar  in,  451 
the  inclined  plane  for  correct- 
ing,  438 
tortion    in,    450 
unusual    forms   of,   451 
porcelain,    components    of,    258 
uses   of  aluminium,    no 
of  platinum,    105 
Dentures,    beaded   or   grooved,    325 
bridge,    552 
continuous-gum,   264 
entire,   213 

on    celluloid   base,    327 
rubber  base,  281 
partial,   on  rubber  base,   317 

retained  in  mouth  by  means  of 

clasps,    17S 
supported  by  atmospheric  pres- 
sure or  adhesion,   198 
Derivation  of  aluminium,   107 
Determining    the    carat    of    any    given 

alloy,  85 
Dies,    metallic,    156 

Babbitt   metal,    174 
counter-,    156,    168 

progressive,    169 
essential    properties    of,    170 
fusible    alloys    for,    175 
manner   of   obtaining   metallic,    156 
materials  used  in  molding  metallic, 

156 
molding,  where  undercuts  are  pres- 
ent,   158 

with   cores,    158 
preparing    and    pouring    metal    for, 

165 

cast    for    molding,    165 
model  previous  to  molding,  156 
securing   mold    for,    157 
type-metal   for,    174 
withdrawing  the  cast,    157 
Draft    or   wind    furnace,    49 
Dry  method  of  refining  gold,  75 
of   refining   silver,    99 


ELECTRICAL  terms,  659 

cataphoric    apparatus,    668 
dental    apparatus,    659 
dry-cell  battery   system,   669 
energy,    658 
engine,    659 
hot-air   syringe,    668 
laboratory   lathe,    661 
mallet,    665 
motor,    659 
mouth    lamp,    666 
oven   or  furnace.   661 
vulcanizer.   665 


674 


INDEX. 


Electricity,  and  its  application  in  dental 
mechanics,  655 
history  of,  655 
Elements  employed  in  refining  gold,  74 
Entire   dentures,    213 

adhesion   of,   213 
antagonizing    model    for,    238, 

243 
arranging    for    temporary,    248 

teeth  for,  249 
articulators    for,    242 
atmospheric  pressure    for,    214 
application       of       atmospheric 

pressure  for,  215 
backing  or  lining  teeth  in,  256 
constructing       and       attaching 

spiral   springs  to,   252 
forming  a  rim  to  the  plates  in, 

251 
forming    the    borders     of    the 

plate  for,  236 
four    basal    temperaments    and 

their   general   indications    in 

making,   225,  226 
grinding    and   adjusting    single 

gum  teeth  in,  247 
investing,   253 
method    of    constructing,    233, 

237 

modifications    in    the    form    of 
plates   for,   235 

on    celluloid   base,    327 
rubber  base,  281 

overcoming  tendency    to  change 
in  form  of  plates  for,  255 

preliminary     observations     on, 
213 

projection  of  lower  jaw  in  se- 
curing  bite   for,    241 

re-posing   of  the   features   for, 

239 
selection    and    arrangement    of 

the  teeth  of  replacement  for, 

220,  228,  249,  842 
soldering   and   finishing,    257 
swaged  metallic  plate-base  for, 

233 
trying  plate  for,  in  mouth  236 
warping  or  springing  of,  254 
lower     dentures,     impressions     for, 

137.    146 
upper     dentures,     impressions     for, 
136,  144 
Extraction   of  teeth,  surgical  treatment 
of  the  mouth  after  the,  123 


FELDSPAR,   259 

Forming  an   air-chamber,    199 
Formulas   for  gold  plate,  8t,  82 
for   gold   solder,   83 


Formulas   for  silver  solder,   102 
Fractured  maxillae,  400 

Angle's  method  of  fixation  for, 

427 
appliances    for    the    correction 

of,  400 
finishing     appliances     for     the 

correction  of,   404 
flasking  for,  403 
forming  splint  in  wax  for,  402 
Kingsley  splint  for,  405 
Ottolengui's    splint   for,    425 
packing  and  vulcanizing  splints 

for,   403 
preparing  the  methods  for,  401 
securing    splint    in    the    mouth 
in,   405 

the  impression  in,  401 
splintage    for    section    of    in- 
ferior, 420 
Fractures    of   the    maxillae,    division    of, 

400 
Franklin's    mold,    166 
Fuels   employed,  gaseous,   28 
liquid,    22 
solid,    2.2 
Furnaces,   49 
baking,   51 
draft   or  wind,   49 
electric,  661 
gas   crucible,   with   blast,   61 

without  blast,   60 
Land's,  56 
Sharpe's,    58 
wind,   49 
Fusible   alloys  of  lead,    114 
Fusing-point  of  aluminium,   108 
of  antimony,    115 
of  bismuth,  116 
of  gold,  70 
of   lead,    114 
of   platinum,    103 
of  silver,   98 
of  tin,    115 
of  zinc,   113 


GAGE   plate,    standard,    94 
Gas  crucible  furnaces,  60,  61 
illuminating,    28 
olefiant,    55 
Gaseous  fuels,  28 

illuminating  gas  as,  28 
oxyhydrogen  gas  as,  30 
Gasolene,   55 

blowpipe,  42 
Gassing  the  body  and  enamel,   53 
General   properties  of  alloys,   117 
of   aluminium,    107 
of  antimony,    115 
of  bismuth,  116 


INDEX. 


675 


General  properties  of  copper,  111 
of   gold,    69 
of  lead,  114 
of  platinum,   103 
of    rubber,    281 
of  silver,  98 
of  tin,  115 
of  zinc,  113 
Generation  and  application  of  heat,  31 
Geographical  distribution  of  gold,  69 
Geological  situations  of  gold,  68 
German  silver,  112 
Gold   alloy   cast   base,    365 
fusing-point   of,    70 
geographical   distribution  of,   69 
geological    situations    of,    68 
influence  of  alloying  and  the  prop- 
erties of,  70 
ingots   of,    89 

manner  of  making,  89 
laminating    or    rolling,    92 
malleability    of,    70 
plate,    formulas    for,    81 

laminating  or  rolling,  92 
required   fineness    of,   80 
thickness  of,  required  for  arti- 
ficial  dentures,   94 
thickness      of,      required      for 
clasps,   backings,    etc.,    94 
properties  of,   69 

of  particular  alloys  of,   71 
raised  to  a  higher  carat,  87 
reduced  to  a  required  carat,  86 
refining,  74 
solders,  83 
wire,  method  of  obtaining,  95 

HAWES  flask,   159 

Heat,  appliances  used  in  the  generation 

and  application  of,  31 
Humid  method  of  refining  gold,  78 

ILLUMINATING  gas  as  a  fuel,  28 
Impressions,   beeswax   for,    129-137 
entire  lower,  137,  146 

upper,   136,   144 
for    interdental    splints,    401 
manner   of  obtaining,    126 
modeling  composition   for,   138 
moldine    for,    138 
partial  lower,   134 

upper,    130 
plaster-of-Paris    for,    139-146 
of   the   mouth,   materials,   etc.,   em- 
ployed in  obtaining,   126 
India-rubber,  general  properties  of,  281 
Influence  of  alloying  on  the  prorerties 

of  gold,  70 
Ingot,   manner  of  procuring,   89 
Interdental  splints,  400 


Introduction,    17 
Iridium,    106 


KAOLIN,  259 

Kingsley's   obturators,   375 
splint,  405 

LABORATORY  uses  of  lead,  114 

Laminating  or   rolling  gold  plate,   92 

Lamps,    32 

Land's   furnace,    56 

Lead,  114 

fusible  alloys  of,  114 

fusing-point  of,   114 

laboratory  uses  of,   114 

properties    of,    114 

soft,   solder,    114 
Lewis's  molding-flask,  160 
Liquid  fuels,   22 
Lower  jaw,  projection  of,  241 

MALLEABILITY  of  gold,  70 
Materials,    etc.,    employed    in    obtaining 

impressions  of  the  mouth,  126 
Maxillae,    appliances   for  the   correction 

of  fractured,  400 
Melotte's  clamp  for  soldering,  48 
Mesial   line,   the,    203 
Melting   aluminium,    109 
Metallic  base  with   rubber  or   celluloid 

attachment,  354 
Metals    employed    in    laboratory    opera- 
tions,  68 
Modeling  composition  as  an  impression 

material,  138 
Models,   plaster,    148 
Moldine  as  an  impression  material,  138 
Molding  by  dry  heat,   343 

in   steam,   340 

materials  used  in,   156 

when  undercuts  are  present,  158 

with  coves,   158 
Molds,  asbestos,  90 

carbon,   91 

charcoal,    90 
Mouth   blowpipe,    34 

OBTURATORS,  375 

Olefiant  gas,   55 
Orthodontia,   434 
Ottolengui's   splint,   425 
Oxycarbon  blowpipe.  42 
Oxyhydrogen   blowpipe,    44 

PALLADIUM,   106 
Parker   swaging   device,    176 
Partial  dentures,  adjusting  clasps  to,  192 
annealing,    191 


6;6 


INDEX. 


Partial  dentures,  constructed  on  a  base 
of  rubber,  317 

lower  impressions  for,  134,  140 
manner     of     forming     an     air- 
chamber    for,    199 
modifications   in   form   of,    187 
reinforcement  of,   189 
retained  in  the  mouth  by  means 

of  clasps,   178 
soldered  air-chamber  in,  200 
supported  by  atmospheric  pres- 
sure or  adhesion,   198 
swaging,    190 

the   form   of  the  base  for,   198 
upper  impressions  of,   130,   140 
use  of  a  tracer  in  the  swaging 
process   for,  200 
or  stay  clasps,   186 
Pearsall    molding-flask,    162 
Plaster  models,   148 

forming  an  air-chamber  on,  151 
manner  of  obtaining,   148,  150, 

152,   154 

Plaster-of-Paris,    139 
derivation   of,    139 
manner   of  preparing,    140 
to  hasten  the  setting  of,  140 

Platinoid  metals,  105 

Platinum,    103 

alloys  of,   105 

fusing-point   of,    103 

general    properties    of,    103 

solder   for,    105 

use   of,   for   dental   purposes,    105 

Polishing  aluminium,   109 

Porcelain  teeth,  258 

coloring  materials   for,   260 
manufacture    of,    261 
components  of  dental,  258 

Preparing   and   pouring  metal   for   dies, 

16s 

casts  for  molding,   165 
model  previous  to  molding,  156 
Principles  of  soldering,  65 
Projection  of  the  lower  jaw,  241 
Properties' of  a  die,  170 

of  particular  alloys  of  gold,   71 


RAISING  gold  to  a  higher  carat,  87 
Reducing  gold  to  a  required  carat,  86 
metals,  80 

silver    to    the    required    forms    for 
dental   purposes,    101 
Reduction    of    gold    solder    into    proper 

form  for  use,  95 
Refining   gold,    74 

elements  employed  in,  74 
dry  method  of,  75 
humid  method  of,  78 


Refining    gold,     separation     of     foreign 
metals  in,  75 
silver,  99 
Regulating     supplemented     by      crown- 
work,  454 
Reinforcement  of  partial   dentures,   189 
Removal  of  flask  after  vulcanizing,  315 
Replacement   of  the   inferior  teeth,    182 
Re-posing  the  features,  239,  456 
Required   fineness    of   gold   plate,   80 

thickness  of  gold  plate,  94 
Rubber  or  vulcanite  base,  281 

arranging     teeth     for, 

284 
finishing    process    for, 

3i5 
flaskiag    for,    288-298 
grinding  and  jointing 

teeth  on,  286 
packing  the  mold   for 

a,   292 
partial    dentures    con- 
structed   on    a,    317 
vulcanizing,      298-315 
celluloid  attachment  for  metal- 
lic  base,   354 
compounding    for    dental    purposes, 

282 
general    properties    of,    281 
metallic   clasps   attached   to,  plates, 

318  _ 
repairing,   plates,    319 
substitution  of  plate  for,  teeth,  319 


SCALLOPED   clasp,   186 
Securing  clasps  to  the  plate,   193 

mold,   157 
Selecting  and  arranging  artificial  teeth, 

204,  220,  228,  249,  284 
Separation  of  foreign  metals  from  gold, 
75 
of  teeth  for  the  reception  of  clasps, 
J82 
Sharpe's   furnace,   58 
Silex,   259 
Silver,  98 

alloys  of,   98 

formulas  for,  solders,   102 

fusing-point   of,   98 

general  properties   of,   98 

reduction  of,  to  required  forms  for 

dental   purposes,    101 
refining,   99 
Soft  solder,    114 
Solder,  brass,  112 

formulas    for   silver,    103 

for   platinum,    105 
gold,    83 

reduction   of,   95 


INDEX. 


677 


Solder,   gold,   reduction   of,   into   proper 
form  for  use,  95 
soft,    114 
Soldered   air-chamber,    200 
Soldering  aluminium,    109 
principles  of,  65 
supports   for,   46 
Solid  fuel,  22 

anthracite   coal   as,   26 
bituminous  coal   as,  24 
charcoal  as,  23 
coke  as,  24 
Solubility  of  aluminium,    108 
Spiral     springs,     constructing     and     at- 
taching, 252 

method    of    constructing,    96 
Springing  or  warping  of   dentures,   254 
Standard    clasp,    185 

gage   plate,    94 
Steam-gage   for  vulcanizer,   314 
Suersen's   obturator,   392 
Supplying   the   loss    of   the   inferior   in- 
cisors,   182 
Supports  for  soldering,  46 

Melotte's  clamp-,  48 
Surgical   treatment   of  the   mouth   after 

the   extraction   of  teeth,    123 
Swaging  the  plate,    190 


TEETH,  manner   of  backing,    208,   256 
for  the  attachment  of  clasps,  180 
grinding,    204,    286 
investing,    208,    253 
manufacture   of  porcelain,   258 
replacement  of  the   inferior,    182 
securing  harmony  of  color  of,  204, 

247 
selecting,    arranging,    and    antagon- 
izing the,  204,  220,  .228,  249,  284 
separation     of,     for     reception     of 

clasps,   182 
soldering   and  finishing,   211 
substitution  of  plate  for  rubber,  319 
surgical   treatment   of   mouth    after 
extraction  of,  123 


Temperaments,  the  four  basal,  and  their 

general  indications,  225,  226 
Temporary  plates,  arranging  for,  248 
Thermometers  as  indicators  of  heat,  313 
Tin,    115 

alloys  of,  115 
fusing-point   of,    115 
properties    of    115 
Treatment  of  defects  of  the  palatal  or- 
gans, 373 
of  the  mouth  preparatory  to  the  in- 
sertion of  artificial  dentures,  120 
Trying  the  plate  in   the  mouth,   236 
Type-metal,   174 

Use  of  a  tracer  in  the  swaging  process, 
200 

clasps,   178 


VACUUM   chamber,    151,    199,   200 
Vulcanite    base-plate    faced    with    cellu- 
loid,  349 
Vulcanizers,  Boston,   309 

electric,  665 

Mann,   307 

Philadelphia,   310 

steam-gage  for,  314 

Whitney,  307 
Vulcanizing,    298-315 

time     and     temperature     necessary 
for,  305 


WARPING    or    springing    of    dentures, 

254 
Wet  method  of  refining  silver,  99 
Wind  or  draft  furnace,   49 
Wire,  method  of  obtaining  gold,  95 
Withdrawing  the  cast,  157 
Wood  as  a  fuel,  23 


ZINC.   113 

dental    uses    of,    113 
fusing-point    of,    113 
sreneral    properties    of.    113 
Zylonite,   353 


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129    Illustrations.     Cloth,   $1.25. 

WHITE.     THE  MOUTH  AND  TEETH.     Illustrated.     Cloth,   .40. 


8ST'  Complete  Descriptive  Catalogues  on  Dental,  Medical,  Pharmaceutical,  and 
Chemical  Books  Sent  upon  Application. 


Catalogue  of  the  Medical,  Dental,  Phar- 
maceutical, Chemical,  and  Scientific  Books 
Published  by  P.  Blakiston's  Son  &  Co., 
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Established  1843. 

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CATALOGUES  AND  CIRCULARS  SENT  FREE  UPON  APPLICATION: 

Catalogue  No.  1. — A  complete  list  of  the  titles  of  all  our  publications  on  Medicine,  Dentistry, 
Pharmacy,  and  Allied  Sciences,  with  Classified  Index. 

Catalogue  No.  3. — Pharmaceutical  Books. 

Catalogue  No.  4. — Books  on  Chemistry  and  Chemical  Technology. 

Catalogue  No.  5. — Books  for  Nurses  and  Lay  Readers. 

Catalogue  No.  6. — Books  on  Dentistry  and  Books  used  by  Dental  Students. 

Catalogue  No.  7. — Books  on  Hygiene  and  Sanitary  Science ;  Including  Water  and  Milk 
Analysis,  Microscopy,  Physical  Education,  Hospitals,  etc. 

Catalogue  No.  8. — List  of  about  300  Standard  Books  classified  by  Subjects. 

Catalogue  No.  9. — Books  on  Nervous  and  Mental  Diseases. 

Catalogue  No.  10. — Books  on  Diseases  of  the  Eye,  Refraction,  Spectacles,  etc. 

A  Genera.1  Catalogue. — Containing  2000  titles  of  Standard  Books  on  Medicine  and  Sur- 
gery.    American  and  English. 

Special  Circulars. — Morris'  Anatomy;  Gould  and  Pyle's  Cyclopedia;  Deaver's  Surgical 
Anatomy;  Tyson's  Practice;  Gould's  Medical  Dictionaries;  Books  on 
the  Eye  ;  Books  on  Diseases  of  the  Nervous  System  ;  The  ?  Quiz- 
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CLASSIFIED  LIST,  WITH  PRICES, 

OF  ALL  BOOKS  PUBLISHED  BY 
P.  BLAKISTON'S  SON  &  CO.,  PHILADELPHIA. 

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ANATOMY. 
Ballou,     Veterinary  Anat.      Jo. 80 
Broomell.       Anatomy     and 

Histol.  of  Mouth  and  Teeth.  4.50 
Campbell.  Dissection  Out- 
lines. -  -  -  -  -  .50 
Deaver.  Surgical  Anatomy.  24.00 
Gordinier.  Anatomy  of  Nerv- 
ous System.  Illustrated.  6.00 
Heath.  Practical.  9th  Ed.  4.25 
Holden.  Dissector.     2  Vols.     3  00 

Osteology.     8th  Ed.      5.25 

Landmarks.     4th  Ed.      .75 

Hughes.     Dissector.    Part  I.  3.C0 

.  Part  II.  -         -         3°° 

Part  III.  -  -  3.00 
Macalister's  Text-Book.  -  5.00 
McMurrich.  Embryology.  3.00 
Minot.  Embryology  -  4.50 
Marshall's  Phys.  &  Anatom- 
ical Diagrams.  $40.00  and  60.00 
Morris.  Text-Book  Anat.      3d 

Ed.  846  111.    Clo., $6.00;  Sh.,  7.00 
Potter.       Compend   of.       6th 

Ed.     133  Illustrations.  -  .80 

Wilson's  Anatomy,  nth  Ed.  5.00 

ANESTHETICS. 
Buxton.     Anesthetics.     -  1.50 

Turnbull.     4th  Ed.  -         2.50 

BACTERIOLOGY. 
Conn.      Agricultural    Bacteri- 
ology.    Illustrated.       -      -     2.50 

Bact.  in  Milk  Products.  1.25 

Emery.  Bacteriolog.  Diag.  1.50 
Hewlett.  Manual  of.  lllus.  4.00 
Williams.     Student's  Manual 

of.     2d  Edition.     90  lllus.       1.50 
Smith.     Bacteriology.      -    -     1.50 

BRAIN  AND  INSANITY. 
Blackburn.     Autopsies.     -       1.25 
Chase.     General  Paresis.  1.75 

Horsley.  Brain  and  Sp.  Cord.  2.50 
Ireland.     Mental    Affections 

of  Children.      -  4.00 

Lewis.  Mental  Diseases.  7.00 
Mann's  Psychological  Med.  3.00 
Regis.  Mental  Medicine.  -  2.00 
Stearns.  Mental  Dis.  lllus.  2.75 
Tuke.  Dictionary  of  Psycho- 
logical Medicine.  2  Vols.  10.00 
Wood.    Brain  and  Overwork.     .40 

CHEMISTRY. 
Ttchnol'g'l  Books.  Water  ,Milk,etc. 
Allen.     Commercial     Organic 


4.50 
3-5o 
3-5o 

4.50 
4.50 
4.50 
4.50 


Analysis.     Vol.  I. 

Vol.  II.     Part  I. 

Vol.  II.     Part  II.      - 

Vol.  II.     Part  III.    - 

Vol.  III.     Parti.     - 

Vol.111.     Part  II.    - 

Vol.  III.     Part  III.- 

Vol.  IV.      -        -       - 

Bailey    and    Cady.      Chein 

Analysis.  •         -        -        -         1.25 
Bartley.    Medical  Chemistry.  3.00 

Clinical  Chemistry.         1.00 

Bloxam's  Text-Book.  9th  Ed. 

Bunge.  Physiologic  and  Path- 
ologic Chemistry.     -         -         3.00 

Caldwell.       Qualitative    and 

Quantitative  Analysis.        -     1.00 
Cameron.     Oils  &  Varnishes.  2.25 

Soap  and  Candles.     -    2.00 

Clowes  and  Coleman.  Quan- 
titative Analysis.     5th  Ed.  -  3.50 

Coblentz.  Volumetric  Anal.  1.25 
Congdon.  Laboratory.  -  1  00 
Gardner.  Brewing,  etc.  -  1.50 
Gray.  Physics,  Vol.  I.  -  4.50 
Groves  and  Thorp.  Chemi- 
cal! echnology.  Vol.  1.  Fuels  5.00 
Vol.  II.     Lighting,     -    4.00 

Vol.  III.   (,;<s  Lighting.  3  50 

Vol.  IV.  Klec.  Lighting.  3.50 

Heusler.     The  Terpenes.  4.00 


Holland.  Urine,  Gastric  Con- 
tents, Poisons  and  Milk  Anal- 
ysis.    6th  Ed.       -        -        -  $1.00 

Leffmann's  Medical  Chem.        .80 

Food  Analysis.      -      -      2.50 

Milk  Analysis.     -      -      1.25 

Water  Analysis.       -         1.25 

Structural  Formulae.        1.00 

Muter.     Pract.  and  Anal.         1.25 
Oettel.     Electro-Chem.  -     .75 

Electro-Chem.  Exper.-      .75 

Richter's  Inorganic.    5th  Ed.    1.75 
Organic.  3d  Ed.  2  Vols. 

Vol.  I.  Aliphatic  Series.    3.00 
Vol.11  Carbocyclic  "        3.C0 
Rockwood.     Chemical  Anal.  1.50 
Smith.  Electro-Chem.  Anal.     1.25 
Smith  and   Keller.     Experi- 
ments.    4th  Ed.     lllus.  .60 
Sutton.     VolumetricAnal.        5.00 
Symonds.     Manual  of.              2.00 
Traube.  Physico-Chem.Meth.  1.50 
Thresh.     Water  Supplies.    -    2.00 
Ulzer  and  Fraenkel.    Tech- 
nical Chemical  Analysis.          1.25 
Woody.  Essentials  of  4th  Ed.  1.50 

CHILDREN. 
Hatfield.  Compend  of.  3d  Ed.   .80 
Power.   Surgical  Diseases  of.  2.50 
Smith.    Wasting  Diseases  of.    2.00 
Starr.    Digestive  Organs  of.       3.00 

Hygiene  of  the  Nursery. 1. 00 

Taylor  and  Wells.  Manual.  4.50 

CLINICAL  CHARTS,  ETC. 
Griffith's     Temp't're  Charts. 

Pads  of  50  -        .  -  .50 

Keen.     Outline    Drawings    of 

Human  Body.     Pads.    -  .25 

Schreiner.    Diet  Lists.    Pads,   .75 


80 


COMPENDS. 
Ballou.     Veterinary  Anat. 
Brubaker's  Physiol,  nth  Ed. 
Cushing.     Histology.     -    - 
Gould  and  Pyle.     The  Eye. 
Hatfield.     Children.     3d  Ed. 
Horwitz.     Surgery.     5th  Ed. 
Hughes.  Practice.  2  Pts.  Ea.    .80 

Kyle.     Ear,  Nose,  Throat.       

Landis.  Obstetrics.  7th  Ed.  .80 
Leffmann's  Chemistry.  4th  Ed.  .80 
Potter's    Anatomy,   6lh  Ed.       .80 

Materia  Medica.  6th  Ed.    .80 

Schamberg.  Skin  Diseases.  .80 
Stewart.  Pharmacy.  5th  Ed.  .80 
Thayer.     General  Pathology.     .80 

Special  Pathology.  .80 

Warren.     Dentistry.    3d  Ed     .80 
Wells.     Gynecology.    2d  Ed.     .80 
Any  of  above,  Interleaved,  $1.00. 
Self  -  Examination.  3500 

Questions   on   Medical    Sub- 
jects. -  -  Paper,    .10 

CONSUMPTION. 
Knopf.  Piilmon. Tuberculosis.  3.00 
Steell.    Physical  Signs  of  Pul- 
monary Disease.      -      -      -     1.25 

DENTISTRY. 
Barrett.     Dental  Surg.    -  1.00 

Broomell.    Anat.  and  Hist,  of 

Mouth  and  Teeth.  -  -  4.50 
Fillebrown.  Op.  Dent.  lllus.  2.25 
Gorgas.      Dental  Medicine.      4.00 

Questions  and  Answers.  6.00 

Harris.     Principles  and  Prac.  6.00 

Dictionary  of.     6th  Ed.  5.00 

Richardson.  Mech.  Dent.  5.00 
Smith.  Dental  Metallurgy.  2.00 
Taft.  Index  of  Dental  Lit.  2.00 
Tomes.     Dental  Surgery,         4.00 

Dental  Anatomy.  4.00 

Warren's  Compend  of.     -  .80 

Dental    Prosthesis  and 

Metallurgy.      lllus.         -  1.25 

White.    Mouth  and  Teeth.         .40 


DIAGNOSIS. 
Brown.     Medical.     4th  Ed.   $2.25 
Tyson's  Manual.  4th  Ed.  lllus.  1.50 

DICTIONARIES.  ETC. 
Gould's  Illustrated  Dictionary 
of  Medicine,  Biology,  and  Al- 
lied Sciences,  etc.     5th  Edi- 
tion.    Leather,  $10.00;   Halt 
Russia,  Thumb  Index,    -      1200 
Gould'sStudent's  Medical  Dic- 
tionary,     nth    Ed.,IUus.,  J£ 
Mor.,  $2.50;    Thumb  Ind.,    3.00 
Gould's    Pocket  Dictionary — 
30,000  medical  words.     4th 
Edition.  Enlarged.  Leather,  1.00 
Gould  and  Pyle.    Cyclopedia 
of  Med.  and  Surg.     One  Vol. 
lllus.  Leather,  10.00 

Gould    and     Pyle's    Pocket 

Cyclopedia  of  Medicine.  1.00 

Harris'  Dental.  Clo.  5.00;  Shp.  6.00 
Longley's  Pronouncing.  .75 

Maxwell.  Terminologia  Med- 
ica Polyglotta.  -        -        3-°° 
Treves.     German-English.        3.25 

EAR. 
Burnett.     Hearing,  etc.  .40 

Hovell.     Treatise  on.  -     5.50 

Kyle.     Ear,  Nose,  Throat.       

Pritchard.  Diseasesof.  3d  Ed.  1.50 

ELECTRICITY. 
Bigelow.     Plain  Talks  on.       1.00 
Hedley.     Therapeutic  Elec.     2.50 
Jacobi.  Electrotherapy.  2V0IS.  5.00 
Jones.     Medical  Electricity.     3.00 

EYE. 
Donders.    Refraction.  -      1.25 

Fick.     Diseases  of  the  Eye.      4.50 
Gould  and  Pyle.   Compend.      .80 
Greeff.     Microscopic  Examin- 
ation of.    -        -        -        -        1.25 
Harlan.     Eyesight.  -  .40 

Hartridge.  Refraction,  nth  Ed.  1. 50 

Ophthalmoscope.4thEd.  1.50 

Hansell  and  Sweet.     Treat- 
ise on  Diseases  of  -  

Hansell   and    Reber.     Mus- 
cular Anomalies  of  the  Eye.  1.50 
Hansell   and    Bell.    Clinical 

Ophthalmology.  120  lllus.  1.50 
Jennings.  Ophthalmoscopy.  1.50 
Morton.  Refraction.  6th  Ed.  1.00 
Ohlemann.  Ocular  Therap.  1.75 
Parsons.  Optics.  -  -  2.00 
Phillips.  Spectacles  and  Eye- 
glasses. 49  lllus.  3d  Ed.  1.00 
Swanzy's  Handbook.  7th  Ed.  2.50 
Thorington.     Retinoscopy.      1.00 

Refraction.     200  lllus.  1.50 

Walker.     Student's  Aid.  1.50 

Wright.     Ophthalmology.        3.00 

GYNECOLOGY. 
Bishop.      Uterine    Fibromyo- 

mata.     Illustrated.       -      -       3.50 
Byford  (H.  T.).     Manual.    3d 

Edition,     363  Illustrations.     3.00 
Diihrssen.     Gynecological 

Practice.     105  Illustrations.    1.50 
Lewers.     Dis.  of  Women.         2.50 

Cancer  of  Uterus.  3.00 

Montgomery.       Text-book 

of.  527  lllus.  -  -  -  5.00 
Roberts.  Gynecological  Path- 
ology. Illustrated.  -  6.00 
Wells.  Compend.  lllus.  .80 
HKAI-TH  AND  DOMESTIC 
MEDICINE. 
Bulkley.  The  Skin.  -  .40 
Burnett.  Hearing.  -  .40 
Cohen.  Throat  and  Voice.  .40 
Dulles.  Emergencies.  5th  Ed.  1.00 
Harlan.  F'.yesight.  -  .40 
Hartshorne.  Our  Homes.  .40 
Osgood.  Dangers  of  Winter.  .40 
Packard.  Sea  Air,  etc.  .40 
Richardson's  Long  Life.  .40 
White.  Mouth  and  Teeth.  .40 
Wilson.     Summer  and  its  Din.  .40 


CLASSIFIED  LIST  OF  P.  BLAKISTON'S  SON  &*  CO.'S  PUBLICATIONS 


HISTOLOGY. 
Cushing.     Compend.     -     -  £0.80 
Stirling.    Histology.    2d  Ed.    2.00 
Stohr's  Histology.  Illus.      -    3.00 

HYGIENE. 
Canfield.   Hygiene  of  the  Sick- 
Room.      -  1.25 

Coplin.     Practical  Hygiene.    

Kenwood.       Public     Health 

Laboratory  Guide.  -         2.00 

Lincoln.  School  Hygiene.  .40 
McFarland.  Prophylaxis.  2.50 
Notter.  Practical  Hygiene.  7.00 
Parkes'  (L.  C),  Manual.  3  00 

Rosenau.     Disinfection  and 

Disinfectants.      Illus.        -      2.00 

Starr.  H  ygiene  of  the  Nursery.  1.00 

Stevenson  and  Murphy.  A 

Treatise  on  Hygiene.     In  3 

Vols.     Circular  Vol.  I,   6.00 

upon  application.      Vol.  II,   6.00 

Vol.  Ill,   5.00 

Thresh.     Water  Supplies.        2.00 

Wilson's  Handbook.  8th  Ed.  3.00 

Weyl.     Coal-Tar  Colors,  1.25 

MASSAGE,  ETC. 
Mitchell  and  Gulick.      Me- 
chanotherapy.    Illustrated.    2.50 
Ostrom.   Massage.  115  Illus.   1.00 

MATERIA  MEDICA. 
Bracken.     Materia  Med.  2.75 

Cobleatz.  Newer  Remedies.  1.00 
Gorgas.  Dental.  5th  Ed.  4.C0 
Groff.  Mat.  Med.  for  Nurses.  1.25 
Heller.     Essentials  of.  -     1.50 

Potter's  Compend  of.  6th  Ed.  .80 
Potter's    Handbook    of.     9th 

Ed.  Cloth,  $5. 00;  Sheep,  6.00 
Sayre.   Organic  Materia  Med. 

and  Pharmacognosy.  -  4.50 
Tavera.     Medicinal  Plants  of 

the  Philippines.        -        -        2.00 
White   and  Wilcox.      Mat. 
Med.,  Pharmacy,  Pharmacol- 
ogy, and  Therapeutics.    5th 
Ed.  Enlarged.  CI., $3.00;  Sh.  3.50 

MEDICAL  JURISPRUDENCE. 
Mann.     Forensic  Med.        -      6.50 
Reese.  Med.  Jurisprudence  and 
Toxicology.  6th  Ed.  #3.00;  Sh.  3.50 

MICROSCOPE. 
Carpenter.     The  Microscope. 

8th  Ed.     850  Illus.           -         8.00 
Greenish.    Microscopical  Ex- 
am, of  Foods  and  Drugs.   -  

Lee.  Vade  Mecum  of.  5th  Ed.  4.00 
Oertel.     Med.  Microscopy.      2x0 
Reeves.  Med.  Microscopy.      2.50 
Wethered.     Medical  Micros- 
copy.    Illus.        ...     2.00 

MISCELLANEOUS. 
Black.     Micro-organisms.  .75 

Burnet.  Food  and  Dietaries.  1.50 
Cohen.     Organotherapy.  2.50 

Da  Costa.  Hematology.  -  5.00 
Davis.  Alimeniotherapy.  2.50 
Fenwick.  Cancer  of  Stom.  3  00 
Goodall    and    Washbourn. 

Infectious  Diseases.  Illus.  3.00 
Gould.     Borderland  Studies.    2.00 

Biographic  Clinics.        1.00 

Greene.  Medical  Examination 

in  Life  Insurance.  Illus.  -  4.00 
Haig.     Uric  Acid.    6th  Ed.      

Diet  and  Food.  4th  Ed.   1.00 

Hare.     Mediastinal  Disease.     2.00 
Hemmeter.  Diseases  of  Stom- 
ach.    2d  Edition.     Illus.     -    6.00 

Diseases  of  Intestines. 

Illustrated.     2  Vols.       -        10.00 

Henry.  Anaemia.  -  -  .50 
McCook.  Amer.  Spiders.  40.00 
New  Sydenham  Society's 

Publications,  each  year.  -  8.00 
Scheube.     Diseases  of  Warm 

Countries.  Illustrated.  -  8  co 
Schofield.  The  Force  of  Mind.  2.00 
Thorne.     Schott  Methods  in 

Heart  Disease.        -        -  2.00 

Tissier.     Pneumatotherapy.     2.50 
Treves.     Physical  Education.    .75 
Weber  and  Hinsdale.     Cli- 
mate.  2  Vols.     Illustrated.     5.00 
Winternitz.     Hydrotherapy.  2.50 


NERVOUS  DISEASES,  ETC. 

Dercum.  Rest,  Mental  Thera- 
peutics, Suggestion.        -       $2  50 

Frenkel.     Tabetic  Ataxia.        3.00 

Gordinier.  Anatomy  of  Cen- 
tral Nervous  System.      -         6.00 

Gowers.  Manual  of.  530  Illus. 
Vol.  I, #4.00  ;  Vol.  II,      -        4.00 

Syphilis  and  the  Ner- 
vous System.       ...      1. 00 

Epilepsy.     New  Ed.        3.00 

Ormerod.  Manual  of.  -  1.00 
Pershing.    Diagnosis  of  Nerv. 

and  Mental  Diseases.        -       1.25 
Preston.     Hysteria.     Illus.      2.00 

NURSING. 

Canfield.  Hygiene  of  the  Sick- 

Room.        -  1.25 

Cuff.  Lectures  on.  3d  Ed.  1.25 
Davis.  Bandaging.  Illus.  1.50 
Domville's  Manual.  8th  Ed.  .75 
Fullerton.     Obst.  Nursing.     1.00 

Surgical  Nursing.  1.00 

Gould.  Pocket  Medical  Dic- 
tionary.    Limp  Morocco.        1.00 

Groff.  Mat.  Med.  for  Nurses.  1.25 
Hadley.  Manual  of.  -  1.25 
Humphrey.  Manual.  23d  Ed.  1.00 
Starr.  Hygieneof theNursery.  1.00 
Temperature  Charts.  Pads.  .50 
Voswinkel.     Surg.  Nursing.   1.00 

OBSTETRICS. 
Cazeauxand  Tarnier.   Text- 
Book  of.     Colored  Plates.        4.50 

Edgar.     Text-book  of.  -    

Landis.  Compend.  6th  Ed.  .80 
Winckel's  Text-book.  5.00 

PATHOLOGY. 
Barlow.     Pathological  Anat.  6.50 
Blackburn.     Autopsies.  1.25 

Coplin.  Manual  of.  3d  Ed.  3.50 
Da  Costa.  The  Blood.  -  5.00 
MacLeod.  Pathology  of  Skin.  6.co 
Roberts.  Gynecological  Path- 
ology. Illustrated.  -  6.00 
Thayer.     General  Pathology      .80 

Special  Pathology.  .80 

Virchow.     Post-mortems.  .75 

Whitacre.    Lab.  Text-book.    1.50 

PHARMACY. 
Beasley's  Receipt-Book.      -    2.00 
^— —  Formulary.      -        -  2.00 

Coblentz.  Manual  of  Pharm.  3.50 
Proctor.  Practical  Pharm.  3.00 
Robinson.  Latin  Grammar  of.  1.75 
Sayre.    Organic  Materia  Med. 

and  Pharmacognosy.  2d  Ed.   4.50 
Scoville.     Compounding.  2.50 

Stewart's  Compend.  5th  Ed.  .80 
U.   S.   Pharmacopoeia.     7th 

Revision.  1890  CI. $2.50;  Sh.,  3.00 

Postage  extra,   .27 

Select  Tables  from  U.S.  P.       .25 

PHYSIOLOGY. 

Birch.  Practical  Physiology.  1.75 
Brubaker's  Compend,  nth  Ed.  .80 
Jones.     Outlines  of.      -        -      1.50 
Kirkes'  New  17th  Ed.    (Halli- 
burton.)   Cloth,  J3.00;   Sh.,  3.75 

Landois'  Text-book.  845  Illus. 

Starling.  Elements  of.  -  1.00 
Stirling.  Practical  Phys.  2.00 
Tyson's  Cell  Doctrine.       -       1.50 

POISONS. 

Reese.  Toxicology.  4th  Ed.  3.00 
Tanner.     Memoranda  of.  .75 

PRACTICE. 
Beale.     Slight  Ailments.  1.25 

Fagge.     Practice.     Vol.1.        6 
Vol.  II,    6 
Fowler's  Dictionary  of.      -      3 
Gould  and  Pyle.    Cyclopedia 

of  Medicine.     Illustrated.      10 
Hughes.  Compend.  2  Pts.  ea. 

Physician's  Edition. 

1  Vol.  Morocco,  Gilt  edge.     2.25 

Taylor's  Manual  of.  6th  Ed. 
Tyson.    The  Practice  of  Medi- 
cine. Illus.  CI.  S5.50:  Sheep     6.50 


SKIN. 

Bulkley.  The  Skin.  -  J0.40 
Crocker.  Dis.  of  Skin.  Illus.  5.00 
MacLeod.  Pathology  of  Skin.  6.00 
Schamberg.     Compend.  .80 

Van   Harlingen.     Diagnosis 

and  Treatment  of  Skin  Dis. 

3d  Ed.     60  Illus.      -        -        2.75 


SURGERY  AND   SURGICAL 

DISEASES. 
Berry.     Thyroid  Gland.      -      4.00 
Butlin.  Surgery  of  Malignant 

Disease.  -  -  4.50 

Davis.     Bandaging.     Illus.       1.50 

Deaver.     Appendicitis.        -    

Surgical  Anatomy.      -  24.00 

Douglas.     Surgical   Diseases 

of  Abdomen.     Illus.      -      -    

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Hamilton.  Tumors.  3d  Ed.  1.25 
Heath's  Minor.    12th  Ed.  1.50 

Clinical  Lectures.        -    2.00 

Horwitz.  Compend.  5th  Ed.  .80 
Jacobson.  Operations  of.  -  10.00 
Keay.  Gall-Stone  Disease.  1.25 
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Macready  on  Ruptures  -  6.00 
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ences in  South  Africa.  -  4.00 
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mentary Canal.  -  -  3.00 
Morris.     Renal  Surgery.  2.00 

Moullin.      Complete     Text- 
book.    3d  Ed.  by  Hamilton. 
600  Illustrations.         -        -     6.00 
Smith.     Abdominal  Surg.        10.00 
Voswinkel.  Surg.  Nursing.      1.00 
Walsham.  Surgery.  7th  Ed.  3.50 


THERAPEUTICS. 

Beasley's  3000  Prescriptions.  2.00 
Coblentz.  New  Remedies.  1.00 
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peutics, n  Volumes.  27.50 
Mays.  Theine.  -  -  .50 
Murray.  Notes  on  Remedies.  1.25 
Potter's  Compend.     6th  Ed.       .80 

Handbook  of  Mat.  Med. 

Phar.  and  Thera.    9th  Ed.     5.00 
White   and    'Wilcox.    Mat. 
Med.,  Pharmacy,  Pharmacol- 
ogy, and  Therap.     5th  Ed.     3.00 


.40 
2.75 
1. 00 


THROAT  AND  NOSE. 

Cohen.     Throat  and  Voice. 
Hall.     Nose  and  Throat.    - 
Hollopeter.     Hay  Fever. 
Knight.     Throat.     Illus.     - 
Kyle.     Ear,  Nose,  Throat. 
McBride.      Clinical  Manual, 

Colored  Plates.     3d  Ed.     -     7.00 
Potter.     Stammering,  etc.         i.oo 


URINE  &  URINARY  ORGANS. 
Acton.     Repro.  Organs.  1.75 

Holland.  The  Urine,  Milk  and 

Common  Poisons.  6th  Ed.  1.00 
Kleen.  Diabetes.  -  -  2.50 
Memminger.     Diagnosis  by 

the  Urine.  2d  Ed.  Illus.  1.00 
Morris.     Renal  Surgery.  2.00 

Moullin.     The  Prostate.     -     1.75 

The  Bladder.         -  1.50 

Scott.      Clinical  and   Micros. 

Examination  of  Urine.  -  5.C0 
Tyson.  Exam,  of  Urine.  1.50 
Van  Niiys.    Urine  Analysis.     1.00 

VENEREAL  DISEASES. 

Gowers.      Syphilis  and    the 

Nervous  System.  -  -  1.00 
Sturgis.    Manual  of.    7th  Ed.  1.25 

VISITING  LISTS. 

Lindsay    and  Blakiston's 
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REVISED  EDITION. 


TYSON'S  PRACTICE 

A  TEXT-BOOK  FOR  PRACTITIONERS  AND  STUDENTS 
WITH  SPECIAL  REFERENCE  TO  DIAGNOSIS  AND  TREATMENT 

By  JAMES  TYSON,  M.D. 

Professor  of  Medicine  in  the  University  of  Pennsylvania ;   Physician  to  the  University  and 
Philadelphia  Hospitals,  etc. 


COLORED  PLATES  AND  125  OTHER  ILLUSTRATIONS 
Octavo.     J222  Pages.     Cloth,  $5.50 ;  Leather,  $6.50 ;  Half  Russia,  $7.50 


The  object  of  this  book  is — first,  to  aid  the  student  and  physician  to  recognize 
disease,  and,  second,  to  point  out  the  proper  methods  of  treatment.  To  this  end 
Diagnosis  and  Treatment  receive  special  attention,  while  pathology  and 
morbid  anatomy  have  such  consideration  as  is  demanded  by  their  importance  as  funda- 
mental conditions  of  a  thorough  understanding  of  disease.  Dr.  Tyson's  qualifications 
for  writing  such  a  work  are  unequaled.  It  is  really  the  outcome  of  over  thirty 
years'  experience  in  teaching  and  in  private  and  hospital  practice.  As  a 
teacher  he  has,  while  devoting  himself  chiefly  to  clinical  medicine,  occupied  several 
important  chairs,  notably  those  of  General  Pathology  and  Morbid  Anatomy,  and 
Clinical  Medicine  in  the  University  of  Pennsylvania,  an  experience  that  has  necessarily 
widened  his  point  of  view  and  added  weight  to  his  judgment.  This,  the  Second, 
Edition  has  been  most  thoroughly  revised,  parts  have  been  rewritten,  new 
material  and  illustrations  have  been  added,  and  in  many  respects  it  may  be  considered 
a  new  book. 

"  It  is  in  the  writing  and  preparation  of  a  work  of  this  character  that  Dr.  Tyson  stands  pre- 
eminent. Those  of  the  profession — and  there  are  many  at  this  time — who  have  been  fortunate  to 
have  been  his  pupils  during  their  medical  student  days,  will  remember  that  he  brought  to  his 
lectures  and  to  his  writings  an  amount  of  induslry  and  care  which  many  other  teachers  failed  to 
bring ;  and  those  who  know  him  best  as  an  author  and  teacher  have  expected  that  his  book  on  the 
Practice  of  Medicine,  when  it  appeared,  would  be  a  credit  to  himself,  and  would  increase  his 
reputation  as  a  medical  author.    This  belief  has  proved  correct. ' ' —  Therapeutic  Gazette,  Detroit,  Mich. 

"  After  a  third  of  a  century  spent  in  the  assiduous  study,  practice,  and  teaching  of  medicine, 
and  the  publication  of  successful  books  on  various  topics,  theoretical  and  practical,  the  writing  of  a 
textbook  is  not  only  a  proper  ambition,  but  is  really  expected  by  students  and  the  profession.  So 
Professor  Tyson  best  shows  his  modesty  by  making  no  apology  for  the  present  work." — American 
Journal  of  Medical  Sciences,  Philadelphia. 

4 


J8@"A11  prices  are  net.     No  discount  can  be  allowed  retail  purchasers. 


P,  BLAKISTON'S  SON  &  CO.'S 

Medical  and  Scientific  Publications. 


Acton.     The  Functions  and  Disorders  of  the  Reproductive  Organs 

in  Childhood,  Youth,  Adult  Age,  and  Advanced  Life,  considered  in  their  Physiological, 
Social,  and  Moral  Relations.   By  Wm.  Acton,  m.d.,  m.r.cs.   8th  Edition.  Cloth,  $1.75 

Allen.     Commercial  Organic  Analysis. 

New  Revised  Editions.  A  Treatise  on  the  Properties,  Proximate  Analytical  Exami- 
nation and  Modes  of  Assaying  the  Various  Organic  Chemicals  and  Products  employed 
in  the  Arts,  Manufactures,  Medicine,  etc.,  with  Concise  Methods  for  the  Detection 
and  Determination  of  Impurities,  Adulterations,  and  Products  of  Decomposition,  etc. 
Revised  and  Enlarged.  By  Alfred  H.  Allen,  f.cs.,  Public  Analyst  for  the  West 
Riding  of  Yorkshire  ;  Past  President  Society  of  Public  Analysts  of  Great  Britain. 

Vol.  I.  Preliminary  Examination  of  Organic  Bodies.  Alcohols,  Neutral  Alcoholic 
Derivatives,  Ethers,  Starch  and  its  Isomers,  Sugars,  Acid  Derivatives  of  Alcohols 
and  Vegetable  Acids,  etc.  Third  Edition,  with  numerous  additions  yb  the 
author,  and  revisions  and  additions  by  Dr.  Henry  Leffmann,  Professor  of 
Chemistry  and  Metallurgy  in  the  Pennsylvania  College  of  Dental  Surgery,  and 
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tables.  Cloth,  $4.50 

Vol.  II — Part  I.  Fixed  Oils,  Fats,  Waxes,  Glycerin,  Soaps,  Nitroglycerin, 
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with  many  useful  tables.  Revised  by  Dr.  Henry  Leffmann,  with  numerous 
additions  by  the  author.  Cloth,  $3.50 

Vol.  II — Part  II.  Hydrocarbons,  Mineral  Oils,  Lubricants,  Asphalt,  Benzene  and 
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Leffmann,  with  additions  by  the  author.  Cloth,  $3. 50 

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Vol.  Ill — Part  I.  Tannins,  Dyes,  Coloring  Matters,  and  Writing  Inks.  Third 
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Coffee,  Cocoa,  Kola,  Cocaine,  Opium,  etc.     Second  Edition.     8vo.    Cloth,  $4. 50 

Vol.  Ill — Part  III.  Vegetable  Alkaloids  concluded,  Non-Basic  Vegetable  Bitter 
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Second  Edition.  Cloth,  $4.50 

Vol.  IV.  Proteids  and  Albuminous  Principles.  Proteoids  or  Albuminoids. 
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Cloth,  $4.50 

Bailey  and  Cady.     Chemical  Analysis. 

Laboratory  Guide  to  the  Study  of  Qualitative  Analysis.  By  E.  H.  S.  Bailey,  Ph.D., 
Professor  of  Chemistry,  and  Hamilton  Cady,  a.b.,  Assistant  Professor  of  Chemistry 
in  the  University  of  Kansas'.     Fourth  Edition.  Cloth,  51.25 

3-23-03.  5 


P.  BLAKISTON'S  SON  &*   CO.'S 


Ballou.     Veterinary  Anatomy  and  Physiology. 

By  Wm.  R.  Ballou,  m.d.,  late  Professor  of  Equine  Anatomy,  New  York  College  of 
Veterinary  Surgeons.  With  29  Graphic  Illustrations.  i2mo.  No.  12  ?Quiz-Co?n- 
pendt  Series.  Cloth,  .80  ;  Interleaved  for  the  Addition  of  Notes,  $1.00 

Barrett.      Dental  Surgery 

for  General  Practitioners  and  Students  of  Medicine  and  Dentistry.  Extraction  of 
Teeth,  etc.     By  A.  W.  Barrett,  m.d.     Third  Ed.     86  Illus.      i2mo.     Cloth,  $1.00 

Bartley.     Medical  and  Pharmaceutical  Chemistry. 

A  Text-Book  for  Medical  and  Pharmaceutical  Students.  By  E.  H.  Bartley,  m.d., 
Professor  of  Chemistry  and  Toxicology  at  the  Long  Island  College  Hospital ;  Dean 
and  Professor  of  Chemistry,  Brooklyn  College  of  Pharmacy  ;  Chief  Chemist,  Board 
of  Health  of  Brooklyn,  N.  Y.  Fifth  Edition,  Revised  and  Improved.  With  Illus- 
trations, Glossary,  and  Complete  Index.      i2mo.  Cloth,  $3.00;  Leather,  $3.50 

"  The  subject-matter  is  excellent.  The  descriptions  are  detailed  and  very  complete.  All  of 
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considered  in  the  light  of  this  purpose,  it  is  hard  to  find  anything  in  it  for  adverse  criticism." — 
Boston  Medical  and  Surgical  Journal. 

Clinical  Chemistry. 

The  Chemical  Examination  of  the  Saliva,  Gastric  Juice,  Feces,  Milk,  Urine,  etc., 
with  Notes  on  Urinary  Diagnosis,  Volumetric  Analysis,  and  Weights  and  Meas- 
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Beale.     On  Slight  Ailments. 

Their  Nature  and  Treatment.  By  Lionel  S.  Beale,  m.d.,  f.r.s.,  Professor  of 
Practice,  King's  Medical  College,  London.     Second  Edition.     8vo.  Cloth,  $1.25 

Beasley's  Book  of  Prescriptions. 

Containing  over  3100  Prescriptions,  collected  from  the  Practice  of  the  most  Eminent 
Physicians  and  Surgeons — English,  French,  and  American  ;  a  Compendious  History 
of  the  Materia  Medica,  Lists  of  the  Doses  of  all  Officinal  and  Established  Prepa- 
rations, and  an  Index  of  Diseases  and  their  Remedies.  By  Henry  Beasley. 
Seventh  Edition.  Cloth,  $2.00 

Druggists'  General  Receipt  Book. 

Comprising  a  copious  Veterinary  Formulary  ;  Recipes  in  Patent  and  Proprietary 
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an  Appendix  of  Useful  Tables.     Tenth  Edition.  Cloth,  $2.00 

Pharmaceutical  Formulary 

and  Synopsis  of  the  British,  French,  German,  and  United  States  Pharmacopoeias. 
Comprising  Standard  and  Approved  Formulae  for  the  Preparations  and  Com- 
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Berry.     The  Thyroid  Gland. 
The    Diseases  of  the   Thyroid  Gland   and  Their   Surgical   Treatment.     By  James 
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Birch.      Practical  Physiology. 
An    Elementary    Class-Book.       Including    Histology,    Chemical   and    Experimental 
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Bishop.      Uterine  Fibromyomata. 

Their  Pathology,  Diagnosis,  and  Treatment.  By  E.  Stanmore  Bishop,  f.r.c.s. 
(Eng.),  President  Manchester  Clinical  Society  ;  Fellow  British  Gynecological  Society. 
Full-page  Plates  and  other  Illustrations.     Octavo.  Cloth,  $3.50 

Black.     Micro-Organisms. 

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By  G.  V.  Black,  m.d.,  d.d.s.  Cloth,  .75 

Blackburn.     Autopsies.     Illustrated. 

A  Manual  of  Autopsies,  Designed  for  the  Use  of  Hospitals  for  the  Insane  and  other 
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Bloxam.     Chemistry  (Inorganic  and  Organic). 

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Bracken.     Outlines  of  Materia  Medica  and  Pharmacology. 

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Broomell.     Anatomy  and  Histology  of  the  Mouth  and  Teeth. 

By  Dr.  I.  N.  Broomell,  Professor  of  Dental  Anatomy,  Dental  Histology,  and  Pros- 
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A  Manual  of  Clinical  Methods.     By  J.  J.  Graham  Brown,  m.d.,  f.r.c.p.,  Lecturer 
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Brubaker.     Compend  of  Physiology.     Eleventh  Edition. 

A  Compend  of  Physiology,  specially  adapted  for  the  use  of  Students  and  Physicians. 
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College  ;  Professor  of  Physiology,  Pennsylvania  College  of  Dental  Surgery,  Philadel- 
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By  L.  Duncan  Bulkley,  m.d.     Illustrated.  Cloth.  .40 

Bunge.     Physiologic  and  Pathologic  Chemistry. 

By  Dr.  C.  Bunge,  Professor  at  Basel.  Authorized  Translation  from  the  Fourth 
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Burnet.     Foods  and  Dietaries. 

A  Manual  of  Clinical  Dietetics.  By  R.  W.  Burnet,  m.d.,  m.r.c.p.,  Physician  to 
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Burnett.     Hearing  and  How  to  Keep  It. 
By  Chas.  H.  Burnett,  m.d.,   Professor  of  Diseases  of  the  Ear  at  the  Philadelphia 
Polyclinic.     Illustrated.  Cloth,  .40 

Butlin.     The  Operative  Surgery  of  Malignant  Disease. 

By  Henry  T.  Butlin,  f.r.c.s.,  Assistant  Surgeon  to,  and  Demonstrator  of  Surgery 
at,  St.  Bartholomew's  Hospital,  London,  etc.,  assisted  by  James  Berry,  f.r.c.s., 
Wm.  Bruce-Clarke,  m.b.,  f.r.c.s.,  A.  H.  G.  Doran,  f.r.c.s.,  Percy  Furnivall, 
f.r.c.s.,  W.  H.  H.  Jessop,  m.b.,  f.r.c.s.,  and  H.  J.  Waring,  b.Sc,  f.r.c.s. 
Second  Edition,  Revised  and  Rewritten.     Illustrated.     Octavo.  Cloth,  $4. 50 

Buxton.     On  Anesthetics. 

A  Manual.  By  Dudley  Wilmot  Buxton,  m.r.c.s.,  m.r.c.p.,  Assistant  to  Professor 
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Byford.     Manual  of  Gynecology.     363  Illustrations. 

By  Henry  T.  Byford,  m.d.,  Professor  of  Gynecology  and  Clinical  Gynecology  in 
the  College  of  Physicians  and  Surgeons  of  Chicago,  and  in  Post-Graduate  Medical 
School,  etc.  Third  Edition,  Revised  and  Enlarged.  363  Illustrations,  many  of  which 
are  from  original  drawings  and  several  of  which  are  Colored.      i2mo. 

Cloth,  $3.00;  Sheep,  $3.50 
Caldwell.     Chemical  Analysis. 

Elements  of  Qualitative  and  Quantitative  Chemical  Analysis.  By  G.  C.  Caldwell, 
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sity, Ithaca,  New  York,  etc.     Third  Edition.     Octavo.  Cloth,  $1.00 

Cameron.     Oils  and  Varnishes. 

By  James  Cameron,  f.i. c.    Illustrations,  Formulae,  Tables,  etc.     nmo,     Cloth,  $2.25 

Soap  and  Candles. 

A  Handbook  for  Manufacturers,  Chemists,  etc.  54  Illustrations.    i2mo.  Cloth,  $2.00 

Campbell.      Dissection  Outline  and  Index. 

A  Systematic  Outline  for  Students  for  the  Dissection  of  the  Human  Body  and  an 
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University  of  Michigan,  Ann  Arbor.     Second  Edition,  Revised.  Cloth,  .50 

Canfield.      Hygiene  of  the  Sick-Room. 

Being  a  Brief  Consideration  of  Asepsis,  Antisepsis,  Disinfection,  Bacteriology,  Immu- 
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on  Clinical  Medicine,  University  of  Maryland,      nmo.  Cloth,  #1 .25 

Carpenter.     The  Microscope  and  Its  Revelations. 

By  W.  B.  Carpenter,  m.d.,  f.r.s.  Eighth  Edition,  by  Rev.  Dr.  Dallinger, 
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1 136  pages.  Cloth,  #8.00;   Half  Morocco,  #9.00 

Chase.     General  Paresis,  Practical  and  Clinical. 

By  Robert  H.  Chase,  m.d.,  Physician-in-chief  Friends'  Asylum  forthe  Insane,  Frank- 
ford,  Philadelphia;  late  Resident  Physician  State  Hospital  for  Insane,  Norristown, 
Pennsylvania,  etc.     Illustrated.     Just  Ready.  Cloth,  #1.75 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS. 


Cazeaux  and  Tarnier's  Midwifery.     With  Appendix,  by  Munde. 

The  Theory  and  Practice  of  Obstetrics,  including  the  Diseases  of  Pregnancy  and 
Parturition,  Obstetrical  Operations,  etc.  By  P.  Cazeaux.  Remodeled,  rearranged, 
and  revised  by  S.  Tarnier,  m.d.  Eighth  American  from  the  Eighth  French  and 
First  Italian  Edition.  Edited  by  Robert  J.  Hess,  m.d.  With  an  Appendix  by  Paul 
F.  Munde,  m.d.  Illustrated  by  Lithographs,  Full-page  Plates,  and  numerous  En- 
gravings.    8vo.  Cloth,  $4.50;  Full  Leather,  $5.50 

Clowes  and  Coleman.     Quantitative  Analysis. 

Adapted  for  the  Use  of  the  Laboratories  of  Schools  and  Colleges.  By  Frank  Clowes, 
Sc.d.,  Emeritus  Professor  of  Chemistry,  University  College,  Nottingham,  and  I. 
Bernard  Coleman,  Assoc.  R.  C.  Sci.,  Dublin,  Professor  of  Chemistry,  Southwest 
London  Polytechnic.     Fifth  Edition.      122  Illustrations.  Cloth,  $3.50 

Coblentz.     Manual  of  Pharmacy. 
A  Text-Book  for  Students.     By  Virgil  Coblentz,  a.m.,  ph.d.,  f.c.s.,  Professor  of 
Chemistry  and  Physics  ;  Director  of  Pharmaceutical  Laboratory,    College  of  Phar- 
macy of  the  City  of  New  York.     Second  Edition,  Revised  and  Enlarged.     437  Illus- 
trations.    Octavo.      572  pages.  Cloth,  $3.50  ;  Sheep,  $4.50 

The  Newer  Remedies. 

Including  their  Synonyms,  Sources,  Methods  of  Preparation,  Tests,  Solubilities, 
and  Doses  as  far  as  known.  Together  with  Sections  on  Organo-Therapeutic 
Agents  and  Indifferent  Compounds  of  Iron.  Third  Edition,  very  much  enlarged. 
Octavo.  Cloth,  $1.00 

Volumetric  Analysis. 

A  Practical  Handbook  for  Students  of  Chemistry.  Including  Indicators,  Test- 
Papers,  Alkalimetry,  Acidimetry,  Analysis  by  Oxidation  and  Reduction,  Iodom- 
etry,  Assay  Processes  for  Drugs  with  the  Titrimetric  Estimation  of  Alkaloids, 
Estimation  of  Phenol,  Sugar,  Tables  of  Atomic  and  Molecular  Weights. 
Illustrated.     8vo.  Cloth,  $1.25 

Cohen.     System  of  Physiologic  Therapeutics.     Illustrated. 

A  Practical  Exposition  of  the  Methods  Other  than  Drug-giving,  Useful  in  the  Treat- 
ment of  the  Sick  and  in  the  Prevention  of  Disease.  Edited  by  Solomon  Solis 
Cohen,  a.m.,  m.d.,  Senior  Assistant  Professor  of  Clinical  Medicine  at  Jefferson 
Medical  College  ;  formerly  Professor  of  Medicine  and  Therapeutics  in  the  Phila- 
delphia Polyclinic  ;  Physician  to  the  Philadelphia  and  Jewish  Hospitals  and  to  the 
Rush  Hospital  for  Consumption  ;  formerly  Lecturer  on  Therapeutics,  Dartmouth 
Medical  College.     To  be  issued  in  Eleven  Compact  Octavo  Volumes. 

By  Subscription  only.     Complete  Set,  Cloth,  $27.50  ;  Half  Morocco,  $38.50 

Electrotherapy.     220  Illustrations.     Two  Volumes.     Ready. 

By  George  W.  Jacoby,  m.d.,  New  York,  Consulting  Neurologist  to  the  German 
Hospital,  to  the  Infirmary  for  Women  and  Children,  to  the  Craig  Colony  for 
Epileptics,  etc.  Special  articles  by  Edavard  Jackson,  a.m.,  m.d.,  Denver, 
Col. ;  Emeritus  Professor  of  Diseases  of  the  Eye  in  the  Philadelphia  Polyclinic  ; 
Member  American  Ophthalmological  Society  ;  Fellow  and  ex-President  American 
Academy  of  Medicine,  etc. — By  William  Scheppegrell,  m.d.,  New  Orleans, 
ex-Vice-President  American  Laryngological,  Rhinological,  and  Otological 
Society. — By  J.  Chalmers  Da  Costa,  m.d.,  Clinical  Professor  of  Surgery  in 
Jefferson  Medical  College  ;  Surgeon  to  the  Philadelphia  and  to  St.  Joseph' s 
Hospitals,  etc. — By  Franklin  H.  Martin,  m.d.,  Professor  of  Gynecology,  Post- 
Graduate  Medical  School  of  Chicago  ;  Gynecologist  Chicago  Charity  Hospital ; 
Chairman  Section  of  Obstetrics  and  Diseases  of  Women  of  the  American  Medi- 
cal Association  (1895),  etc. — By  A.  H.  Ohmann-Dumesnil,  m.d.,  Editor  St. 
Louis  Medical  and  Surgical  Journal ;  Member  International  Dermatological 
Congress  ;  formerly  Professor  of  Dermatology,  St.  Louis  Medical  College,  etc. 


10  P.  BLAKIS TON'S  SO  A'   6-   CO.' S 

Cohen.     Physiologic  Therapeutics. — Continued. 

Climatology   and   Health    Resorts,   Including   Mineral    Springs. 
Two  Volumes,  with  Colored  Maps.     Ready. 

By  F.  Parkes  Weber,  m.a.,  m.d.,  f.r.cp.  (Lond.),  Physician  to  the  German 
Hospital,  Dalston  ;  Assistant  Physician  North  London  Hospital  for  Consump- 
tion ;  Author  of  "The  Mineral  Waters  and  Health  Resorts  of  Europe  ;'•'  and 
Guy  Hinsdale,  a.m.,  m.d.,  Secretary  of  the  American  Climatological  Associa- 
tion ;  President  of  the  Pennsylvania  Society  for  the  Prevention  of  Tuberculosis, 
etc.  Including  an  article  on  Hawaii  by  Titus  Munson  Coan,  m.d.,  of  New 
York.  With  Colored  Maps,  prepared  by  Dr.  W.  F.  R.  Phillips,  of  the  U.  S. 
Weather  Bureau,  Washington,  D.  C. 

Prophylaxis — Personal    Hygiene — Civic   Hygiene — Care  of  the 

Sick.      Illustrated.     Ready. 

By  Dr.  Joseph  McFarland,  Professor  of  Pathology,  Medico-Chirurgical  College, 
Philadelphia  ;  Dr.  Henry  Leffmann,  Professor  of  Chemistry  in  the  Woman's 
Medical  College,  Philadelphia;  Albert  Abrams,  a.m.,  m.d.  (University  of 
Heidelberg),  formerly  Professor  of  Pathology,  Cooper  Medical  College,  San 
Francisco  ;  and  Dr.  W.  Wayne  Babcock,  Lecturer  on  Pathology  and  Bac- 
teriology, Medico-Chirurgical  College,  Philadelphia. 

Dietotherapy  :   Food  in  Health  and  Disease.     Ready. 

By  Nathan  S.  Davis,  Jr.,  a.m.,  m.d.,  Professor  of  Principles  and  Practice  of 
Medicine  in  Northwestern  University  Medical  School ;  Physician  to  Mercy  Hos- 
pital, Chicago  ;  Member  American  Academy  of  Medicine,  American  Climato- 
logical Society,   etc.     With  Tables  of  Dietaries,   Relative  Value  of  Foods,  etc. 

Mechanotherapy  and  Physical  Education.  Illustrated. 
By  John  Kearsley  Mitchell,  m.d.,  Assistant  Physician  to  the  Orthopedic 
Hospital  and  Infirmary  for  Nervous  Diseases  ;  Assistant  Neurologist  Presbyterian 
Hospital,  Philadelphia,  etc. ,  formerly  Lecturer  on  Symptomology  at  the  Univer- 
sity of  Pennsylvania;  and  Luther  Gulick,  m.d.,  of  Brooklyn,  N.  Y.,  formerly 
of  Springfield,  Mass.,  Mem.  American  Association  for  Advancement  of  Physical 
Education,  Amer.  Medical  Association,  etc.  With  a  Chapter  on  Orthopedic 
Appliances  by  James  K.  Young,  m.d.,  Professor  of  Orthopedic  Surgery,  Phila- 
delphia Polyclinic  ;  Instructor  in  Orthopedic  Surgery,  University  of  Pennsylvania  ; 
and  an  Article  on  Ocular  Orthopedics  by  Walter  L.  Pyle,  m.d. 

Rest — Mental  Therapeutics — Suggestion. 

By  Francis  X.  Dercum,  m.  d.,  Clinical  Professor  of  Nervous  Diseases  in  Jeffer- 
son Medical  College  ;  Neurologist  to  the  Philadelphia  Hospital  ;  Consulting 
Neurologist  to  St.  Agnes'  Hospital  ;  Neurologist  to  the  Jewish  Hospital  of  Phila- 
delphia. 

Hydrotherapy  —  Thermotherapy  —  H  eliotherapy  —  Crounother- 
apy — Phototherapy — Balneology.     Ready. 

By  Dr.  Wilhelm  Winternitz,  Professor  of  Clinical  Medicine  in  the  University 
of  Vienna  ;  Director  of  the  General  Polyclinic  in  Vienna,  etc. ;  assisted  by 
Dr.  Alois  Strasser,  Instructor  in  Clinical  Medicine,  University  of  Vienna  ; 
and  Dr.  B.  Buxbaum,  Chief  Physician  of  the  Hydrotherapeutic  Institute  of 
Vienna  ;  and  Dr.  E.  Heinrich  Kisch,  Professor  in  the  University  of  Prague  ; 
Physician  at  Marienbad  Spa.  With  Special  Chapters  by  Dr.  A.  C.  Peale,  of  the 
National  Museum,  Washington,  D.  C,  Dr.  J.  H.  Kellogg,  Battle  Creek, 
Mich.,  and  Harvey  Cusiiing,  m.d.,  Johns  Hopkins  Hospital,  Baltimore,  and 
an  Appendix  by  Dr.  COHEN. 

Pneumotherapy  and  Inhalation  Methods.      Illustrated.       Ready. 

By  Dr.  Paul  Tissier,  Chief  of  Clinic  of  the  Faculty  of  Medicine  of  Paris. 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  11 


Cohen.     Physiologic  Therapeutics. — Continued. 

Serotherapy — Organotherapy — Blood-Letting,  etc. — Principles  of 
Therapeutics — Digest — I  ndex. 

By  Joseph  McFarland,  m.d.,  Professor  of  Pathology  in  the  Medico-Chirurgical 
College,  Philadelphia  ;  Pathologist  to  the  Medico  Chirurgical  Hospital,  etc. — 
O.  T.  Osborne,  m.d.,  Professor  of  Materia  Medica  and  Therapeutics,  Medical 
Department,  Yale  University,  New  Haven. — Frederick  A.  Packard,  m.d., 
Visiting  Physician  to  the  Pennsylvania  and  to  the  Children's  Hospitals. — The 
Editor,  and  Augustus  A.  Eshner,  m.d.,  Professor  of  Clinical  Medicine  in  the 
Philadelphia  Polyclinic  ;  Physician  to  the  Philadelphia  Hospital,  etc. 
*#*  Complete  descriptive  circular  upon  application. 

"  There  is  surely  room  for  just  such  a  set  of  books.  We  have  been  too  prone  to  think  that  we 
were  teaching  therapeutics  sufficiently  when  we  taught  our  students  the  old  materia  medica  and  the 
use  of  mere  drugs,  forgetful  and  careless  of  the  importance  of  the  therapeutic  value  of  the  methods 
of  which  this  series  of  books  will  speak." — Johns  Hopkins  Hospital  Bulletin. 

Cohen.     The  Throat  and  Voice. 

By  J.  Solis  Cohen,  m.d.     Illustrated.      i2mo.  Cloth,  .40 

Congdon.      Laboratory  Instructions  in  General  Chemistry. 

By  Ernest  A.  Congdon,  Professor  of  Chemistry  in  the  Drexel  Institute,  Philadelphia  ; 
Member  American  Chemical  Society  ;  Fellow  of  the  London  Chemical  Society,  etc. 
With  an  Appendix,  useful  Tables,  and  56  Illustrations.  Interleaved,  Cloth,  $1.00 

Conn.     Agricultural  Bacteriology. 

Including  a  Study  of  Bacteria  as  Relating  to  Agriculture,  with  Special  Reference  to 
the  Bacteria  in  Soil,  in  the  Dairy,  in  Food  Products,  in  Domestic  Animals,  and  in 
Sewage.  By  H.  W.  Conn,  Ph.D.,  Professor  of  Biology,  Wesleyan  University, 
Middletown,  Conn.;  Author  of  "Evolution  of  To-day,"  "  The  Story  of  Germ  Life," 
etc.     With  Illustrations.  Cloth,  $2. 50 

Bacteria  in  Milk  and  Its  Products. 

Designed  for  Students  of  Dairying,  Boards  of  Health,  Bacteriologists,  and  all 
concerned  in  the  Handling  of  Milk,  Butter,  and  Cheese.  Illustrated,  nmo. 
Just  Ready.  Cloth,  $  1.25 

Coplin.     Manual  of  Pathology.     Third  Edition.     330  Illustrations. 

Including  Bacteriology,  the  Technic  of  Post-mortems,  and  Methods  of  Pathologic 
Research.  By  W.  M.  Late  Coplin,  m.d.,  Professor  of  Pathology  and  Bacteriology, 
Jefferson  Medical  College  ;  Pathologist  to  Jefferson  Medical  College  Hospital  and  to 
the  Philadelphia  Hospital ;  Bacteriologist  to  the  Pennsylvania  State  Board  of  Health. 
Third  Edition,  Rewritten  and  Enlarged.  330  Illustrations,  many  of  which  are  origi- 
nal, and  7  Colored  Plates.     8vo.  Cloth,  $3.50 

Practical  Hygiene. 

With  Special  Articles  on  Plumbing,  Ventilation,  etc.  138  Illustrations.  8vo. 
Second  Edition.  In  Preparation. 

Crocker.     Diseases  of  the  Skin.     Third  Edition. 

Their  Description,  Pathology,  Diagnosis,  and  Treatment,  with  Special  Reference  to 
the  Skin  Eruptions  of  Children.  By  H.  Radcliffe  Crocker,  m.d.,  Physician  to 
the  Department  of  Skin  Diseases,  University  College  Hospital,  London.  Third  Edi- 
tion, Thoroughly  Revised,  with  new  Illustrations.     Just  Ready.  Cloth,  $5.00 

Cuff.      Lectures  on  Medicine  to  Nurses. 
By  Herbert  Edmund  Cuff,  m.d.,  late  Assistant  Medical  Officer,  Stockwell  Fever 
Hospital,  England.     Third  Edition,  Revised.     With  25  Illustrations.        Cloth,  $1.25 


12  P.  BLAKISTON'S  SON  &*   CO.'S 

Cushing.     Compend  of  Histology. 

Specially  adapted  for  the  use  of  Medical  Students  and  Physicians.  By  H.  H.  Cushing, 
m.d.,  Director  of  Histological  and  Embryological  Laboratories,  Woman's  Medical 
College  of  Pennsylvania  ;  Demonstrator  of  Histology  and  Embryology,  Jefferson 
Medical  College,  Philadelphia.  Illustrated.  No.  ly  ?  Quis-Coinfiend?  Series. 
i2mo.      In  Press.  Cloth,  .80  ;  Interleaved  for  Notes,  $1.00 

Davis.      Dietotherapy.     Food  in  Health  and  Disease. 

See  Cohen,  Physiologic  Therapeutics,  page  10. 

Davis.     The  Principles  and  Practice  of  Bandaging. 

By  Gwilym  G.  Davis,  m.d.,  m.r.c.s.,  Universities  of  Pennsylvania  and  Gottingen, 
Assistant  Demonstrator  of  Surgery,  University  of  Pennsylvania  ;  Surgeon  to  the  Out- 
Patient  Departments  of  the  Episcopal  and  Children's  Hospitals  ;  Assistant  Surgeon 
to  the  Orthopaedic  Hospital.  Second  Edition,  Revised  and  Rewritten.  163  Illustra- 
tions, Redrawn  specially  for  this  edition.  Cloth,  $1.50 

Domville.      Manual  for  Nurses 

and  Others  Engaged  in  Attending  to  the  Sick.  By  Ed.  J.  Domville,  m.d.  Ninth 
Edition,  Revised.     With  Recipes  for  Sick-room  Cookery,  etc.      i2mo.  In  Press. 

Donders.      Refraction.     Portrait  of  Author. 

An  Essay  on  the  Nature  and  the  Consequences  of  Anomalies  of  Refraction.  By  F. 
C.  Donders,  m.d.  Authorized  Translation.  Revised  and  Edited  by  Charles  A. 
Oliver,  a.m.,  m.d.  (Univ.  Pa.),  one  of  the  Attending  Surgeons  to  the  Wills  Eye 
Hospital.     With  a  Portrait  of  the  Author.     Octavo.  Half  Morocco,  Gilt,  #1.25 

Da  Costa.     Clinical  Hematology.     Colored  Plates. 

A  Practical  Guide  to  the  Examination  of  the  Blood  by  Clinical  Methods,  with  Refer- 
ence to  the  Diagnosis  of  Disease.  By  John  C.  Da  Costa,  Jr.,  m.d.,  Assistant 
Demonstrator  of  Clinical  Medicine  in  the  Jefferson  Medical  College,  Philadelphia  ; 
Assistant  in  the  Medical  Clinic,  Jefferson  Medical  College  Hospital  ;  Haematologist 
to  the  German  Hospital.  With  six  Colored  Plates  and  48  other  Illustrations.  Octavo. 
Just  Ready.  Cloth,  $5.00;  Sheep,  $6.00 

Deaver.     Surgical  Anatomy.     499  Full-page  Plates.      Now  Ready. 

A  Treatise  on  Human  Anatomy  in  its  Application  to  the  Practice  of  Medicine  and 
Surgery.  By  John  B.  Deaver,  m.d.,  Surgeon-in-Chief  to  the  German  Hospital; 
Surgeon  to  the  Children's  Hospital  and  to  the  Philadelphia  Hospital;  Consulting 
Surgeon  to  St.  Agnes',  St.  Timothy's,  and  Germantown  Hospitals  ;  formerly  Assistant 
Professor  of  Applied  Anatomy,  University  of  Pennsylvania,  etc.  With  499 
very  handsome  Full-page  Illustrations  engraved  from  original  drawings  made  by 
special  artists  from  dissections  prepared  for  the  purpose  in  the  dissecting-rooms  of  the 
University  of  Pennsylvania.  Three  large  volumes.  Royal  square  octavo.  Sold  by 
Subscription.     Orders  taken  for  complete  sets  only.      Description  upon  Application. 

Half  Morocco  or  Sheep,  $24.00  ;  Half  Russia,  $27.00 

Synopsis  of  Contents. 
Volume  I. — Upper  Extremity — Back  of  Neck,  Shoulder,  and  Trunk — Cranium 

— Scalp — Face. 
Volume  II. — Neck — Mouth,    Pharynx,    Larynx,   Nose — Orbit — Eyeball — Organ 

of  Hearing — Brain — Female  Perineum — Male  Perineum. 
Volume  III. — Abdominal   Wall — Abdominal   Cavity — Pelvic    Cavity — Chest — 

Lower  Extremity. 

fi^F*  See  next  page  for  Reviews. 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  13 

Deaver's  Surgical  Anatomy 


The  illustrations,  which  at  the  first  glance  appear  as  the  prominent  feature  of 
the  book-— but  which  in  reality  do  not  overshadow  the  text — consist  of  a  series  of 
pictures  absolutely  unique  and  fresh.  They  will  bear  comparison  from  an  artistic  point 
of  view  with  any  other  work,  while  from  a  practical  point  of  view  there  is  no  other 
volume  or  series  of  volumes  to  which  they  can  be  compared.  When  originally  an- 
nounced, the  book  was  to  contain  two  hundred  illustrations.  As  the  work  of  prepara- 
tion progressed,  this  number  gradually  increased  to  nearly  five  hundred  full-page 
plates,  many  of  which  contain  more  than  one  figure.  With  the  exception  of 
a  few  minor  pictures  made  from  preparations  in  the  possession  of  the  author,  they  have 
all  been  drawn  by  special  artists  from  dissections  made  for  the  purpose  in  the  dissecting- 
rooms  of  the  University  of  Pennsylvania.  Their  accuracy  cannot  be  questioned,  as 
each  drawing  has  been  submitted  to  the  most  careful  scrutiny. 

From  The  Medical  Record,  New  York. 

"  The  reader  is  not  only  taken  fay  easy  and  natural  stages  from  the  more  superficial  to  the 
deeper  regions,  but  the  various  important  regional  landmarks  are  also  indicated  by  schematic 
tracing  upon  the  limbs.  Thus  the  courses  of  arteries,  veins,  and  nerves  are  indicated  in  a  way  that 
makes  the  lesson  strikingly  impressive  and  easily  learned.  No  expense,  evidently,  has  been 
spared  in  the  preparation  of  the  work,  judging  from  the  number  of  full-page  plates  it  contains,  not 
counting  the  smaller  drawings.  Most  of  these  have  been  '  drawn  by  .special  artists  from  dissections 
made  for  the  purpose  in  the  dissecting-rooms  of  the  University  of  Pennsylvania.'  In  summing  up 
the  general  excellences  of  this  remarkable  work,  we  can  accord  our  unqualified  praise  for  the 
accurate,  exhaustive,  and  systematic  manner  in  which  the  author  has  carried  out  his  plan,  and  we 
can  commend  it  as  a  model  of  its  kind,  which  must  fae  possessed  to  be  appreciated." 

From  The  Philadelphia  Medical  Journal. 

"  Many  members  of  the  profession  to  whom  Dr.  Deaver  is  well  known  either  personally  or  by 
reputation  as  a  surgeon,  writer,  teacher,  and  practical  anatomist,  have  awaited  the  appearance  of 
his  Surgical  Anatomy  with  the  expectation  of  finding  in  it  a  guide  in  this  difficult  branch  of  medi- 
cine of  much  more  than  ordinary  practical  value,  and  their  expectations  will  not  be  disappointed/' 

From  The  Journal  of  the  American  Medical  Association. 

"  In  order  to  show  its  thoroughness,  it  is  only  necessary  to  mention  that  no  less  than  twelve 
full-page  plates  are  reproduced  in  order  to  accurately  portray  the  surgical  anatomy  of  the  hand, 
and  it  is  doubtful  whether  any  better  description  exists  in  any  work  in  the  English  language/' 

From  The  Southern  California  Practitioner. 

"  Aside  from  the  merit  of  this  great  work,  it  will  be  a  delight  to  the  lover  of  books.  Its  gen 
eral  make-up  shows  the  highest  development  of  the  book-making  art.  The  bibliophile,  when 
holding  one  of  these  volumes  in  his  hands,  would  be  as  careful  with  it  as  though  he  were  handling 
an  infant,  and  to  drop  it  would  cause  him  the  keenest  pain.  The  illustrations,  the  print,  and  the 
paper  and  binding  are  each  and  all  delightful  in  themselves,  and  yet  the  text  is  concise  and  clear, 
and  taken  with  the  illustrations  make  a  remarkably  good  substitute  for  the  dissecting-room.  To 
have  these  three  volumes  on  his  library  shelves  will  be  a  source  of  pride  and  joy  and  profit  to 
every  practitioner.  Dr.  Deaver  has  in  these  volumes  conferred  a  boon  upon  the  medical  profession 
which  has,  at  least,  never  been  surpassed  by  any  one." 

From  The  New  Orleans  Medical  and  Surgical  Journal. 

"  While  the  needs  of  the  undergraduate  have  been  fully  kept  in  view,  it  has  been  the  aim  of 
the  author  to  provide  a  work  which  would  be  sufficient  for  reference  for  use  in  actual  practice.  We 
believe  the  book  fulfils  both  requirements.  The  arrangement  is  systematic  and  the  discussion  of 
surgical  relations  thorough." 

giir  Large  Descriptive  Circular  will  be  sent  upon  application 


14  P.  BLAKISTON'S  SON  &*   CO.' S 

Deaver.     Appendicitis.     Third  Edition. 

Its  History,  Anatomy,  Etiology,  Pathology,  Symptoms,  Diagnosis,  Prognosis,  Treat- 
ment, Complications,  and  Sequelae.  With  22  Plates,  10  of  which  are  Colored. 
Third  Edition,  Revised  and  Rewritten.  Preparing. 

Dercum.     Rest — Mental  Therapeutics — Suggestion. 

See  Cohen,  Physiologic  Therapeutics,  page  10. 

Douglas.     Surgical  Diseases  of  the  Abdomen. 

By  Richard  Douglas,  m.d.,  late  Professor  of  Gynecology  and  Abdominal  Surgery, 
Medical  Department  Vanderbilt  University  ;  Ex-President  of  the  Southern  Surgical 
and  Gynecological  Association,  etc.  Illustrated  by  19  Full-page  Plates.  Large  Octavo. 
900  pages.  Just  Ready. 

Diihrssen.     A  Manual  of  Gynecological  Practice. 

By  Dr.  A.  DChrssen,  Privat-Docent  in  Gynecology  in  the  University  of  Berlin. 
Translated  from  the  Fourth  German  Edition  and  Edited  by  John  W.  Taylor,  f.r.cs., 
Surgeon  to  the  Birmingham  and  Midlands  Hospital  for  Women  ;  and  Frederick 
Edge,  m.d.,  f.r.cs.     With  105  Illustrations.      i2mo.  Cloth,  $1.50 

Dulles.     What  to  Do  First  In  Accidents  and  Poisoning. 

By  C.  W.  Dulles,  m.d.,  Surgeon  to  the  Rush  Hospital  ;  formerly  Assistant  Surgeon 
2d  Regiment  N.  G.  Pa.,  etc.  Fifth  Edition,  Enlarged.  With  new  Illustrations. 
i2mo.  Cloth,  $1.00 

Edgar.     The  Practice  of  Obstetrics. 

By  J.  Clifton  Edgar,  m.d.,  Professor  of  Obstetrics  Medical  Department  of  Cornell 
University,  New  York  City  ;  Physician  to  Mothers'  and  Babies'  Hospital,  and  to  the 
Emergency  Hospital,  etc.  With  many  Illustrations,  a  large  number  of  which  are 
Original.     Octavo.  Nearly  Ready. 

Emery.     A  Handbook  of  Bacteriological  Diagnosis. 

By  W.  d'Este  Emery,  m.d.,  b.Sc.  Lond.,  Lecturer  in  Pathology  and  Bacteriology  in 
the  University  of  Birmingham.     With  two  colored  plates  and  32  other  illustrations. 

Cloth,  #1.50 

Fagge.      Practice  of  Medicine. 

A  Text-Book  of  Medicine  by  the  late  C.  Hilton  Fagge,  m.d.  Fourth  Edition, 
Revised  and  Edited  by  P.  H.  Pye-Smith,  m.d.,  Consulting  Physician  to  Guy's 
Hospital,  London,  etc.     Two  Vols.     8vo.     Vol.  I,  Cloth,  $6.00  ;  Vol.  II,  Cloth,  $6.00 

Fenwick.     Cancer  of  Stomach. 

By  Samuel  Fenwick.,  m.d.,  m.r.c.p.,  Physician  to  the  London  Hospital,  etc.,  and 
W.  Soltan  Fenwick,  m.d.,  ij.s.  Cloth,  #3.00 

Pick.      Diseases  of  the  Eye  and  Ophthalmoscopy. 

By  Dr.  Eugen  Fick,  University  of  Zurich.  Authorized  Translation  by  A.  B.  Hale, 
m.d.,  Consulting  Ophthalmic  Surgeon  Charity  Hospital,  Chicago  ;  late  Vol.  Assistant 
Imperial  Eye  Clinic,  University  of  Kiel.  Glossary  and  158  Illustrations,  many  of 
which  are  in  Colors.     8vo.  Cloth,  #4.50;  Sheep,  #5.50 

Fillebrown.     A  Text-Book  of  Operative  Dentistry. 

Written  by  invitation  of  the  National  Association  of  Dental  Faculties.  By  Thomas 
FILLEBROWN,  m.d.,  d.m.d.,  Professor  of  Operative  Dentistry  in  the  Dental  School  of 
Harvard  University.      Illustrated.     8vo.  Cloth,  $2.25 

Fowler's  Dictionary  of  Practical  Medicine. 

By  Various  Writers.  An  Encyclopedia  of  Medicine.  Edited  by  James  Kingston 
Fowler,  M.D.,  F.R.C.P.,  Senior  Assistant  Physician  to  the  Middlesex  Hospital, 
London.      8vo.  Cloth,  #3.00;   Half  Morocco,  $4.00 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  15 

Frenkel.     Tabetic  Ataxia. 

Its  Treatment  by  Systematic  Exercise.  By  Dr.  H.  S.  Frenkel.  Authorized  Trans- 
lation by  L.  Freyberger,  m.d.,  m.r.c. p.      132  Illustrations.     Octavo.     Cloth,  $3.00 

Fullerton.     Obstetric  Nursing. 

By  Anna  M.  Fullerton,  m.d.,  Demonstrator  of  Obstetrics  in  the  Woman's  Medical 
College  ;  Obstetrician  and  Gynecologist  to  the  Woman's  Hospital,  Philadelphia,  etc. 
41  Illustrations.     Fifth  Edition,  Revised  and  Enlarged.      i2mo.  Cloth,  $1.00 

Surgical  Nursing. 

Comprising  the  Regular  Course  of  Lectures  upon  Abdominal  Surgery,  Gyne- 
cology, and  General  Surgical  Conditions  delivered  at  the  Training  School  of 
the  Woman's  Hospital,  Philadelphia.  Third  Edition,  Revised.  69  Illustrations. 
i2mo.  Cloth,  $1.00 

Gardner.     The  Brewer,  Distiller,  and  Wine  Manufacturer. 

A  Handbook  for  all  interested  in  the  Manufacture  and  Trade  of  Alcohol  and  its 
Compounds.     Edited  by  John  Gardner,  f.c.s.     Illustrated.  Cloth,  $1.50 

Goodall  and  Washbourn.     A  Manual  of  Infectious  Diseases. 

By  Edward  W.  Goodall,  m.d.  (London),  Medical  Superintendent  Eastern  (Fever) 
Hospital,  Homerton,  London,  etc.  ;  and  J.  W.  Washbourn,  f.r.c.p.,  Assistant 
Physician  to  Guy's  Hospital  and  Physician  to  the  London  Fever  Hospital.  Illustra- 
ted with  Charts,  Diagrams,  and  Full-page  Plates.  Cloth,  §3.00 

Gould.      The    Illustrated    Dictionary    of    Medicine,    Biology,    and 
Allied  Sciences.     Fifth  Edition. 

Being  an  Exhaustive  Lexicon  of  Medicine  and  those  Sciences  Collateral  to  it : 
Biology  (Zoology  and  Botany),  Chemistry,  Dentistry,  Pharmacology,  Microscopy, 
etc.  By  George  M.  Gould,  a.m.,  m.d.,  Editor  of  American  Medicine ;  President, 
1893-94,  American  Academy  of  Medicine,  etc.  With  many  Useful  Tables  and  numer- 
ous Fine  Illustrations.      Large  Square  Octavo.      1633  pages.     Fifth  Edition. 

Full  Sheep  or  Half  Dark-Green  Leather,  $10.00 
With  Thumb  Index,  $11.00;  Half  Russia,  Thumb  Index,  $12.00 

"Few  persons  read  dictionaries  as  Theophile  Gautier  did — for  pleasure;  if,  however,  all 
dictionaries  were  as  readable  as  the  one  under  consideration,  his  taste  for  this  kind  of  literature 
would  be  less  singular.  .  .  .  The  book  is  excellently  printed,  and  the  illustrations  are  admir- 
ably executed.  The  binding  is  substantial  and  even  handsome,  but  the  business-like  '  get-up  '  of 
the  book  makes  it  well  fitted  for  use  as  well  as  for  the  adornment  of  a  book-shelf." — The  British 
Medical  Journal,  London. 

The  Student's  Medical   Dictionary.     Eleventh  Ed.     Illustrated. 

Enlarged.  Including  all  the  Words  and  Phrases  generally  used  in  Medicine, 
with  their  proper  Pronunciations  and  Definitions,  based  on  Recent  Medical 
Literature.  With  Tables  of  the  Bacilli,  Micrococci,  Leukomains,  Ptomains, 
etc.,  of  the  Arteries,  Muscles,  Nerves,  Ganglia,  and  Plexuses;  Mineral  Springs 
of  the  U.  S.,  etc.,  and  a  new  Table  of  Eponymic  Terms  and  Tests.  Rewritten, 
Enlarged,  and  Improved.    With  many  Illustrations.    Small  octavo.   840  pages. 

Half  Morocco,  $2.50;  Thumb  Index,  $3.00 

"  One  pleasing  feature  of  the  book  is  that  the  reader  can  almost  invariably  find  the  definition 
under  the  word  he  looks  for,  without  being  referred  from  one  place  to  another,  as  is  too  commonly 
the  case  in  medical  dictionaries.  The  tables  of  the  bacilli,  micrococci,  leukomains,  and  ptomains 
are  excellent,  and  contain  a  large  amount  of  information  in  a  limited  space.  The  anatomical  tables 
are  also  concise  and  clear.  .  .  .  We  should  unhesitatingly  recommend  this  dictionary  to  our 
readers,  feeling  sure  that  it  will  prove  of  much  value  to  them." — The  American  Journal  of 
Medical  Science. 


16  P.  BLAKISTON'S  SON  &*   CO.'S 

Gould.    The  Pocket  Pronouncing  Medical  Lexicon.    Fourth  Edition. 
(30,000  Medical  Words  Pronounced  and  Defined.) 

A  Student's  Pronouncing  Medical  Lexicon.  Containing  all  the  Words,  their  Defini- 
tions and  Pronunciations,  that  the  Student  generally  comes  in  contact  with  ;  also 
elaborate  Tables  of  the  Arteries,  Muscles,  Nerves,  Bacilli,  etc.,  etc.;  a  Dose  List  in 
both  English  and  Metric  Systems,  a  new  table  of  Clinical  Eponymic  Terms,  etc., 
arranged  in  a  most  convenient  form  for  reference  and  memorizing.  Thin  64mo. 
(6x  3^  inches.)  838  pages.  The  System  of  Pronunciation  used  in  this  book  is  very 
sirnple.  Full  Limp  Leather,  Gilt  Edges,  $1.00  ;  With  Thumb  Index,  $1.25 

"  This  '  Dictionary  '  is  admirably  suited  to  the  uses  of  the  lecture-room,  or  for  the  purposes  of 
a  medical  defining  vocabulary — many  of  the  words  not  yet  being  found  in  any  other  dictionary, 
large  or  small,  while  all  of  the  words  are  those  of  the  living  medical  literature  of  the  day." — The 
Virginia  Medical  Monthly. 

*^*  145,000  copies  of  Gould's  Dictionaries  have  been  sold. 
Sample  pages  and  descriptive  circulars  of  Gould' s  Dictionaries  free  upon  application. 

Biographic  Clinics. 

The  Origin  of  the  Ill-Health  of  DeOuincy,  Carlyle,  Darwin,  Huxley,  and  Brown- 
ing.     i2mo.     Just  Ready.  Cloth,  $1.00 

Borderland  Studies. 

Miscellaneous  Addresses  and  Essays  Pertaining  to  Medicine  and  the  Medical 
Profession,  and  their  Relations  to  General  Science.   35opages.   i2mo.  Cloth,  $2.00 

Gould  and   Pyle.     Cyclopedia   of  Practical    Medicine  and   Surgery. 
72  Special  Contributors.     Illustrated.     One  Volume. 

A  Concise  Reference  Handbook,  Alphabetically  Arranged,  of  Medicine,  Surgery, 
Obstetrics,  Materia  Medica,  Therapeutics,  and  the  various  specialties,  with  Particular 
Reference  to  Diagnosis  and  Treatment.  Compiled  under  the  Editorial  Supervision 
of  Drs.  George  M.  Gould  and  W.  L.  Pyle.  Illustrated.  Large  Square  Octavo. 
Uniform  with  Gould's  "Illustrated  Dictionary."  Full  Sheep  or  Half  Dark-Green 
Leather,  $10.00;  With  Thumb  Index,  $11.00;  Half  Russia,  Thumb  Index,  $12.00 

*„*  The  great  success  of  Dr.  Gould's  "Illustrated  Dictionary  of  Medicine"  sug- 
gested the  preparation  of  this  companion  volume,  which  should  be  to  the  physician  the 
same  trustworthy  handbook  in  the  broad  field  of  general  information  that  the  Dictionary 
is  in  the  more  special  one  of  the  explanation  of  words  and  the  statement  of  facts.  The 
aim  has  been  to  provide  in  a  one-volume  book  all  the  material  usually  contained  in  the 
large  systems  and  much  which  they  do  not  contain.  Instead  of  long,  discursive  papers 
on  special  subjects  there  are  short,  concise,  pithy  articles  alphabetically  arranged,  giv- 
ing the  latest  methods  of  diagnosis,  treatment,  and  operating — a  working  book  in  which 
the  editors  and  their  collaborators  have  condensed  all  that  is  essential  from  a  vast 
amount  of  literature  and  personal  experience. 

The  seventy-two  special  contributors  have  been  selected  from  all  parts  of  the 
country  in  accordance  with  their  fitness  for  treating  special  subjects  about  which  they 
may  be  considered  expert  authorities.  They  are  all  men  of  prominence,  teachers, 
investigators,  and  writers  of  experience,  who  give  to  the  book  a  character  unequaled  by 
any  other  work  of  the  kind. 

"The  book  is  a  companion  volume  to  Gould's  'Illustrated  Dictionary  of  Medicine,'  which 
every  physician  should  possess.  With  these  two  books  in  his  library,  every  busy  physician  will  save 
a  vast  amount  of  time  in  having  at  hand  an  instant  reference  cyclopedia  covering  every  subject  in 
surgery  and  medicine."  —  Chicago  Medical  Recorder. 

Pocket  Cyclopedia  of  Medicine  and  Surgery. 

Based  upon  Gould  and  Pyle's  Cyclopedia  of  Practical  Medicine  and  Surgery. 
Uniform  with  Gould's  Pocket  Dictionary. 

Full  Limp  Leather,  Gilt  Edges,  $1.00  ;  With  Thumb  Index,  $1.25 
$&&"  See  next  page  for  List  of  Contributors. 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS. 


17 


Gould   and   Pyle's   Cyclopedia  of  Medicine 
LIST  OF  CONTRIBUTORS 


Samuel  W.  Abbott,  A.M.,  M.D.,  Boston. 

James  M.  Anders,  M.D.,  LL.D.,  Phila. 

Joseph  D.  Bryant,  M.D.,  New  York. 

James  B.  Bullitt,  M.D.,  Louisville. 

Charles  H.  Burnett,  A.M.,  M.D.,  Phila. 

J.  Abbott  Cantrell,  M.D.,  Philadelphia. 

Archibald  Church,  M.D.,  Chicago. 

L.  Pierce  Clark,  M.D.,  Sonyea,  N.  Y. 

Solomon  Solis-Cohen,  M.D.,  Philadelphia. 

Nathan  S.  Davis,  Jr.,  M.D.,  Chicago. 

Theodore  Diller,  M.D.,  Pittsburg. 

Augustus  A.  Eshner,  M.D.,  Philadelphia. 

J.  T.  Eskridge,  M.D.,  Denver,  Col. 

J.  McFadden  Gaston,  A. B.,  M.D.,  Atlanta, 
Ga. 

J.  McFadden  Gaston,  Jr.,  A.M.,  M.D.,  At- 
lanta, Ga. 

Virgil  P.  Gibney,  M.D.,  New  York. 

George  M.  Gould,  A.M.,  M.D.,  Phila. 

W.  A.  Hardaway,  A.M.,  M.D.,  St.  Louis. 

John  C.  Hemmeter,  M.B.,  M.D.,  Baltimore. 

Barton  Cooke  Hirst,  M.D.,  Philadelphia. 

Bayard  Holmes,  M.D.,  Chicago. 

Orville  Horwitz,  B.S.,  M.D.,  Philadelphia. 

Daniel  E.  Hughes,  M.D.,  Philadelphia. 

James  Nevins  Hyde,  A.M.,  M.D.,  Chicago. 

E.  Fletcher  Ingals,  A.M.,  M.D.,  Chicago. 

Abraham  Jacobi,  M.D.,  New  York. 

William  W.  Johnston,  M.D.,  Washington, 
D.  C. 

Wyatt  Johnston,  M.D.,  Montreal. 

Allen  A.  Jones,  M.D.,  Buffalo. 

William  W.  Keen,  M.D.,  LL.D.,  Phila. 

Howard  S.  Kinne,  M.D.,  Philadelphia. 

Ernest  Laplace,  M.D.,  Philadelphia. 

Benjamin  Lee,  M.D.,  Philadelphia. 

Charles  L.  Leonard,  M.D.,  Philadelphia. 

James  Hendrie  Lloyd,  A.M.,  M.D.,  Phila. 

J.  W.  MacDonald,  M.D.  (Edin.),  F.R.C.S. 
Ed.,  Minneapolis. 

L.  S.  McMurtry,  M.D.,  Louisville. 

G.  Hudson  Makuen,  Philadelphia. 


Matthew  D.  Mann,  M.D.,  Buffalo. 

Henry    O.    Marcy,    A.M.,     M.D.,     LL.D., 

Boston. 
Rudolph  Matas,  M.D.,  New  Orleans. 
Joseph  M.  Mathews,  M.D.,  Louisville. 
John  K.  Mitchell,  M.D.,  Philadelphia. 
Harold  N.  Moyer,  M.D.,  Chicago. 
John  H.  Musser,  M.D.,  Philadelphia. 
A.  G.  Nicholls,  M.D.,  Montreal. 

A.  H.     Ohmann-Dusmesnil,     M.D.,     St. 
Louis. 

William  Osier,  M.D.,  Baltimore. 

Samuel    O.    L.  Potter,  A.M.,  M.D.,  M.R. 

C.P.  (London),  San  Francisco. 
Walter  L.  Pyle,  A.M.,  M.D.,  Philadelphia. 

B.  Alexander  Randall,  A.M.,  M.D.,  Phila. 
Joseph  Ransohoff,  M.D.,  F.R.C.S.  (Eng.), 

Cincinnati. 
Jay  F.  Schamberg,  A.M.,  M.D.,  Phila. 
Nicholas  Senn,  M.D.,  LL.D.,  Chicago. 
Richard  Slee,  M.D.,  Swiftwater,  Pa. 
S.    E.    Solly,    M.D.,    M.R.C.S.,     Colorado 

Springs,  Col. 
Edmond  Souchon,  M.D.,  New  Orleans. 
Ward  F.  Sprenkel,  M.D.,  Philadelphia. 
Charles  G.  Stockton,  M.D.,  Buffalo. 
John  Madison  Taylor,  A.M.,  M.D.,  Phila. 
William  S.  Thayer,  M.D.,  Baltimore. 
James  Thorington,  A.M.,  M.D.,  Phila. 
Martin  B.  Tinker,  M.D.,  Philadelphia. 
James  Tyson,  M.D.,  Philadelphia. 
J.  Hilton  Waterman,  M.D.,  New  York. 
H.  A.  West,  M.D.,  Galveston,  Texas. 
J.  William  White,  M.D.,  PH.D.,  Phila. 
Reynold  W.  Wilcox,  M.A.,  M.D.,  LL.D., 

New  York. 

George  Wilkins,  M.D.,  Montreal. 
DeForest  Willard,  M.D.,  Philadelphia. 
Alfred  C.  Wood,  M.D.,  Philadelphia. 
Horatio  C.  Wood,  M.D.,  LL.D.,  Phila. 
Albert  Woldert,  PH.G.,  M.D.,  Phila. 
James  K.  Young,  M.D.,  Philadelphia. 


"  It  is  difficult  to  describe  the  volume  before  us,  and  one  must  imagine  all  that  is  clinical 
at  the  present  day  as  being  briefly  and  yet  sufficiently  set  forth  under  an  alphabetical 
arrangement,  with  frequent  illustrations,  with  many  formulae  and  diagnostic  distinctions,  and 
with  perfect  homogeneity  ;  then  he  will  have  a  fair  picture  of  the  work.  We  feel  sure,  however, 
that  many  of  our  readers  will  make  the  better  acquaintance  of  the  book  by  becoming  its  possessors, 
and  we  commend  it  to  them  without  hesitation.  We  have  yet  to  find  wherein  it  is  erroneous  or 
disappointing,  and  we  regard  it  as  of  unlimited  value  to  the  average  medical  man."  —  The 
Nezu   York  Medical  Journal. 

*#*  Sample  pages  and  description  upon  application. 


18  P.  BLAKIS TON'S  SON  &*   CO.'S 

Gould  and  Pyle.     Compend  of  Diseases  of  the  Eye. 

Including  Refraction  Treatment  and  Operations,  with  a  Section  on  Local  Therapeutics. 
With  Formulae,  Glossary,  and  several  Tables.  By  Drs.  George  M.  Gould  and 
W.  L.  Pyle.  Second  Edition.  109  Illustrations,  several  of  which  are  Colored. 
No.  S  ? Quiz- Compend?  Series.  Cloth,  80.;  Interleaved  for  Notes,  $1.00 

Gordinier.     The  Gross  and  Minute  Anatomy  of  the  Central  Nervous 

System.     261  Illustrations. 

By  H.  C.  Gordinier,  a.m.,  m.d.,  Professor  of  Physiology  and  of  the  Anatomy  of 
the  Nervous  System  in  the  Albany  Medical  College  ;  Member  American  Neurological 
Association.  With  48  Full-page  Plates  and  213  other  Illustrations,  a  number  of 
which  are  printed  in  Colors  and  many  of  which  are  original.     Large  8vo. 

Handsome  Cloth,  $6.00  ;  Sheep,  $7.00  ;  Half  Russia,  $8.00 

Gorgas'  Dental  Medicine. 

A  Manual  of  Dental  Materia  Medica  and  Therapeutics.  By  Ferdinand  J.  S.  Gorgas, 
m.d.,  d.d.s.,  Professor  of  the  Principles  of  Dental  Science,  Oral  Surgery,  and  Dental 
Mechanism  in  the  Dental  Department  of  the  University  of  Maryland.  Seventh 
Edition,  Revised  and  Enlarged,  with  many  Formulae.     8vo.     Just  Ready. 

Cloth,  $4.00  ;  Sheep,  $5.00  ;  Half  Russia,  $6.00 

Questions  and  Answers. 

Embracing  the  Curriculum  of  the  Dental  Student.  Divided  into  three  parts. 
By  Ferdinand  J.  S.  Gorgas,  a.m.,  m.d.,  d.d.s.,  Author  of  "  Dental  Medicine," 
Editor  of  ' '  Harris'  Principles  and  Practice  of  Dentistry  ' '  and  ' '  Harris'  Dictionary 
of  Medical  Terminology  and  Dental  Surgery,"  Professor  of  the  Principles  of 
Dental  Science,  Oral  Surgery,  etc.,  in  the  University  of  Maryland,  Dental 
Department,  Baltimore,     Octavo.     Just  Ready.  Cloth,  $6.00 

Gray.     A  Treatise  of  Physics. 

By  Andrew  Gray,  ll.d.,  f.r.s.,  Professor  of  Natural  Philosophy  in  the  University 
of  Glasgow.      In  Three  Volumes. 

Vol.  I.     Dynamics   and    Properties   of  Matter.     350  Illustrations.     Octavo. 
688  pages.  Cloth,  $4.50 

GreefF.     The  Microscopic  Examination  of  the  Eye. 

By  Professor  R.  Greeff.  Surgeon  :o  the  Ophthalmic  Department  of  the  Royal  Charite" 
Hospital,  Berlin.  Translated  from  the  Second  German  Edition  by  Hugh  Walker, 
m.a.,  m.d.,  Assistant  Surgeon  and  Pathologist  to  the  Ophthalmic  Department  of  the 
Glasgow  Royal  Infirmary.      i2mo.  Cloth,  $1.25 

Greene.     The  Medical  Examination  for  Life  Insurance 

and  its  Associated  Clinical  Methods.  With  Chapters  on  the  Insurance  of  Sub- 
standard Risks  and  Accident  Insurance.  By  Charles  Lyman  Greene,  m.d.,  of  St. 
Paul,  Clinical  Professor  of  Medicine  and  Physical  Diagnosis  in  the  University  of  Min- 
nesota. With  99  Illustrations,  many  of  which  are  original,  several  being  printed 
in  Colors.     Second  Edition,  Revised.     Octavo.  In  Press. 

Griffith's  Graphic  Clinical  Chart. 

Designed  by  J.  P.  Crozer  Griffith,  m.d.,   Instructor  in  Clinical  Medicine  in  the 
University  of  Pennsylvania.    Sample  copies  free.    Put  up  in  loose  packages  of  50,  .50 
I 'rice  to  Hospitals:   500  copies,  #4.00;    1000  copies,  $7.50. 

Groff.      Materia  Medica  for  Nurses. 

With  Questions  for  Self-examination.  By  John  E.  Gkoff,  Apothecary  in  the  Rhode 
Island  Hospital,  Providence  ;  Professor  of  Materia  Medica,  Botany,  and  Pharma- 
cognosy  in  the  Rhode  Island  College  of  Pharmacy.  Second  Edition,  Revised  and 
Improved.      i2mo.     Just  Ready.  Cloth,  $1.25 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  19 

Greenish.      Microscopical  Examination  of  Foods  and  Drugs. 

Being  a  systematically  arranged  Course  of  Practical  Instruction  in  the  Methods 
adopted  in  the  Analysis  of  Foods  and  Drugs  by  means  of  the  Microscope,  iucluding 
a  description  of  the  structure  of  the  more  important.  Designed  for  the  use  of  Analysts, 
Pharmacists,  and  Students  training  for  those  Professions.  By  Henry  G.  Greenish, 
f.i.c.  ,  f.l.s.,  Professor  of  Pharmaceutics  to  the  Pharmaceutical  Society  of  Great 
Britain.     With  many  Illustrations.     Octavo.  Nearly  Ready. 

Groves  and  Thorp.     Chemical  Technology. 

A  New  and  Complete  Work.     The  Application  of  Chemistry  to  the  Arts  and  Manu- 
factures.    Edited  by  Charles  E.  Groves,   f.r.s.,  and  Wm.  Thorp,  b.sc,  f.i.c, 
assisted  by  many  experts.    With  numerous  Illustrations.     Each  volume  sold  separately. 
-Vol.      I.     Fuel  and  Its  Applications.     607  Illustrations  and  4  Plates.     Octavo. 

Cloth,  $5.00;   y2  Mor.,  $6.50 

Vol.     II.     Lighting.     Candles,  Oils,   Lamps,   etc.     By  W.  Y.  Dent,  L.  Field, 

Boverton   Redwood,  and  D.  A.   Louis.     Illustrated. 

Octavo.  Cloth,  $4.00;   y2  Mor.,  $5.50 

Vol.  III.     Gas    Lighting.     By  Charles    Hunt,    Manager  of  the  Birmingham 

Gasworks.     Illustrated.     Octavo. 

Cloth,  $3.50;  y2  Mor.,  $4.50  . 
Vol.  IV.  Electric  Lighting  and  Photometry.  By  Arthur  G.  Cooke,  m.a., 
Head  of  the  Physics  and  Electric  Engineering  Department 
at  the  Battersea  (London)  Polytechnic  ;  and  W.  J.  Dibdin, 
f.i.c.,  f.c.s.,  late  Chemist  and  Superintending  Gas  Ex- 
aminer, London  County  Council.  With  10  Plates  and  181 
ol her  Illustrations.   Octavo.   Cloth,  $3.50  ;  l/z  Mor.,  $4.50 

Gowers.     Manual  of  Diseases  of  the  Nervous  System. 
A  Complete  Text-Book.     By  Sir  William  R.  Gowers,  m.d.,  f.r.s.,  Physician  to 
National  Hospital  for  the  Paralyzed  and    Epileptic,   etc.     Revised   and    Enlarged. 
With  many  new  Illustrations.     Two  volumes.     Octavo. 

Vol.    I.     Diseases  of  the  Nerves  and  Spinal  Cord. 

Third  Edition.  Cloth,  $4.00  ;  Sheep,  $5.00  ;  Half  Russia,  $6.00 

Vol.  II.     Brain  and   Cranial   Nerves;    General   and    Functional 
Diseases. 

Second  Edition.  Cloth,  $4.00  ;  Sheep,  $5.00  ;  Half  Russia,  $6.00 

*%*  This  book  has  been  translated  into  German,  Italian,  and  Spanish.     It  is  pub- 
lished in  London,  Milan,  Bonn,  Barcelona,  and  Philadelphia. 

Syphilis  and  the  Nervous  System. 

Being  a  Revised  Reprint  of  the  Lettsomian  Lectures  for  1890,  delivered  before 
the  Medical  Society  of  London.      i2mo.  Cloth,  $1.00 

Epilepsy  and  Other  Chronic  Convulsive  Diseases. 

Their  Causes,  Symptoms,  and  Treatment     Second  Edition.  Cloth,  $3.00 

Hadley.     General  Medical  and  Surgical  Nursing. 

A  Manual  for  Nurses.  By  Dr.  W.  G.  Hadley,  Physician  to,  and  Lecturer  on 
Medicine  to  the  Nurses  at,  the  London  Hospital.  With  an  Appendix  on  Sick-Room 
Cookery.      i2mo.      326  pages.  Cloth,  $1.25 

Haig.     Causation  of  Disease  by  Uric  Acid.     Sixth  Edition. 

A  Contribution  to  the  Pathology  of  High  Arterial  Tension,  Headache,  Epilepsy, 
Mental  Depression,  Gout,  Rheumatism,  Diabetes,  Bright' s  Disease,  Anaemia,  etc. 
By  Alexander  Haig,  m.a.,  m.d.  (Oxon.),  f.r.c.p.,  Physician  to  Metropolitan  Hos- 
pital, London.     75  Illustrations.     Fifth  Edition.      8vo.  In  Press. 

Diet  and  Food. 

Considered   in    Relation  to  Strength  and    Power  of  Endurance,   Training  and 
Athletics.     Fourth  Edition,  Revised.      7  Illustrations.  Cloth,  $1.00 


20  P.  BLAKISTON'S  SON  &*   CO.' S 

Hall.     Diseases  of  the  Nose  and  Throat. 

By  F.  de  Havillaxd  Hall,  m.d.,  f.r.c.p.  (Lond.),  Physician  to  the  Westminster 
Hospital  ;  President  of  the  Laryngological  Society  of  London  ;  Joint  Lecturer  on  the 
Principles  and  Practice  of  Medicine  at  the  Westminster  Hospital ;  and  Herbert 
Tilley,  m.d.,  b.s.  (Lond.),  f.r.c.s.  (Eng.),  Surgeon  to  the  Throat  Hospital,  Golden 
Square  ;  Lecturer  on  Diseases  of  the  Nose  and  Throat,  London  Post-Graduate  College 
and  Polyclinic.  Second  Edition,  Revised,  with  2  Plates  and  80  Illustrations.  Cloth,  $2.75 

Hamilton.      Lectures  on  Tumors 

from  a  Clinical  Standpoint.  By  John  B.  Hamilton,  m.d.,  ll.d.,  late  Professor  of 
Surgery  in  Rush  Medical  College,  Chicago  ;  Surgeon  Presbyterian  Hospital,  etc. 
Third  Edition,  Revised.     With  New  Illustrations.      i2mo.  Cloth,  $1.25 

Hansell  and  Sweet.     Diseases  of  the  Eye. 

A  Treatise  on  the  Principles  and  Practice  of  Ophthalmic  Medicine  and  Surgery.  By 
Howard  F.  Hansell,  a.m.,  m.d.,  Clinical  Professor  of  Ophthalmology,  Jefferson 
Medical  College  ;  Professor  of  Diseases  of  the  Eye,  Philadelphia  Polyclinic  and 
College  for  Graduates  in  Medicine  ;  Ophthalmic  Surgeon,  Philadelphia  Hospital,  etc., 
and  William  M.  Sweet,  m.d.,  Instructor  in  Ophthalmology,  Jefferson  Medical 
College  ;  Assistant  Attending  Surgeon  and  Chief  of  Eye  Clinic,  Jefferson  Medical 
College  Hospital ;  Associate  in  Ophthalmology,  Philadelphia  Polyclinic  ;  Ophthalmic 
Surgeon,  Phcenixville  Hospital,  etc.     With  over  200  Illustrations.  In  Press. 

Hansell  and  Reber.      Muscular  Anomalies  or  the  Eye. 

By  Howard  F.  Hansell,  a.m.,  m.d.,  Clinical  Professor  of  Ophthalmology,  Jefferson 
Medical  College  ;  Professor  of  Diseases  of  the  Eye,  Philadelphia  Polyclinic,  etc. ;  and 
Wendell  Reber,  m.d.,  Instructor  in  Ophthalmology,  Philadelphia  Polyclinic,  etc. 
With  1  Plate  and  28  other  Illustrations.      i2mo.  Cloth,  $1.50 

Hansell  and  Bell.     Clinical  Ophthalmology. 

By  Howard  F.  Hansell,  a.m.,  m.d.,  and  James  H.  Bell,  m.d.  With  Colored  Plate 
of  Normal  Fundus  and  120  Illustrations.      i2mo.  Cloth,  $1.50 

Hare.      Mediastinal  Disease. 

The  Pathology,  Clinical  History,  and  Diagnosis  of  Affections  of  the  Mediastinum 
other  than  those  of  the  Heart  and  Aorta.  By  H.  A.  Hare,  m.d.,  Professor  of 
Mat.  Med.  and  Therap.  in  Jefferson  Med.  College.     8vo.     Illustrated.     Cloth,  $2.00 

Harlan.      Eyesight 
and  How  to  Care  for  It.     By  George  C.  Harlan,  m.d.,  Professor  of  Diseases  of 
the  Eye,  Philadelphia  Polyclinic.      Illustrated.  Cloth,  .40 

Harris'  Principles  and  Practice  of  Dentistry. 

Including  Anatomy,  Physiology,  Pathology,  Therapeutics,  Dental  Surgery,  and 
Mechanism.  By  Chapin  A.  Harris,  m.d.,  d.d.s.,  late  President  of  the  Baltimore 
Dental  College;  Author  of  "Dictionary  of  Medical  Terminology  and  Dental  Sur- 
gery." Thirteenth  Edition,  Revised  and  Edited  by  Ferdinand  J.  S.  Gorgas, 
a.m.,  M.D.,  d.d.s.,  Author  of  "Dental  Medicine;"  Professor  of  the  Principles  of 
Dental  Science,  Oral  Surgery,  and  Dental  Mechanism  in  the  University  of  Maryland. 
1250  Illustrations.      1 180  pages.     8vo.  Cloth,  #6.00;  Leather,  $7.00 

Dictionary  of  Dentistry. 

Including  Definitions  of  such  Words  and  Phrases  of  the  Collateral  Sciences  as 
Pertain  to  the  Art  and  Practice  of  Dentistry.  Sixth  Edition,  Rewritten,  Re- 
vised, and  Enlarged.  By  Ferdinand  J.  S.  Gorgas,  m.d.,  d.d.s.,  Author  of 
"  Dental  Medicine  ;"  Editor  of  Harris'  "  Principles  and  Practice  of  Dentistry  ;" 
Professor  of  Principles  of  Dental  Science,  Oral  Surgery,  and  Prosthetic  Dentistry 
in  the  University  of  Maryland.     Octavo.  Cloth,  #5.00;  Leather,  $6.00- 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  21 

Hartridge.     Refraction. 

The  Refraction  of  the  Eye.  A  Manual  for  Students.  By  Gustavus  Hartridge, 
f.r.c.s.,  Senior  Surgeon  Royal  Westminster  Ophthalmic  Hospital  ;  Ophthalmic 
Surgeon  to  St.  Bartholomew's  Hospital,  etc.  105  Illustrations  and  Sheet  of  Test 
Types.     Eleventh  Edition,  Revised  and  Enlarged.  Cloth,  $1.50 

On  the  Ophthalmoscope. 

A  Manual  for  Physicians  and  Students.     Fourth  Edition,  Revised.     With  Colored 
Plates  and  68  Wood-cuts.      i2mo.  Cloth,  $1.50 

Hartshorne.     Our  Homes. 

Their  Situation,  Construction,  Drainage,  etc.  By  Henry  Hartshorne,  m.d.  Illus- 
trated. Cloth,  .40 

Hatfield.     Diseases  of  Children. 
By  Marcus  P.  Hatfield,  Professor  of  Diseases  of  Children,  Chicago  Medical  Col- 
lege.    With  a  Colored  Plate.     Third  Edition.     Being  No.  14  ?  Quiz-  Compend  ?  Series. 
i2mo.     Just  Ready.  Cloth,  .80;  Interleaved  for  the  Addition  of  Notes,  $1.00 

"  Dr.  Hatfield  seems  to  have  most  thoroughly  appreciated  the  needs  of  students,  and  most 
excellently  has  he  condensed  his  matter  into  available  form.  It  is  in  accord  with  the  most  recent 
teachings,  and  while  brief  and  concise,  is  surprisingly  complete.  .  .  .  It  is  free  from  irritating 
repetition  of  questions  and  answers  which  mars  so  many  of  the  compends  now  in  use.  Written  in 
systematic  form,  the  consideration  of  each  disease  begins  with  its  definition,  and  proceeds  through 
the  usual  subheadings  to  prognosis  and  treatment,  thus  furnishing  a  complete,  readable  text-book." 
— Annals  of  Gynecology  and  Pediatry. 

Heath.     Minor  Surgery  and  Bandaging. 
By  Christopher  Heath,  f.r.c.s.,  Holme  Professor  of  Clinical  Surgery  in  Univer- 
sity College,  London.     Twelfth  Edition,  Revised  and  Enlarged  by  Bilton  Pollard, 
f.r.c.s.,   Surgeon    University  College    Hospital,    London.     With    195    Illustrations, 
Formulae,  Diet  List,  etc.      i2mo.  Cloth,  $1.50 

Practical  Anatomy. 

A  Manual  of  Dissections.     Ninth  edition,  Edited  by  H.  Ernest  Lane,  f.r.c.s. 
With  321  Illustrations,  of  which  32  are  Colored.  Cloth,  $4.25 

Clinical  Lectures  on  Surgical  Subjects. 

Second  series.     Delivered  at  University  College  Hospital.  Cloth,  $2.00 

Hedley.     Therapeutic  Electricity  and  Practical  Muscle  Testing. 

By  W.  S.  Hedley,  m.d.,  m.r.c.s.,  in  charge  of  the  Electrotherapeutic  Department 
of  the  London  Hospital.     99  Illustrations.     Octavo.  Cloth,  $2.50 

Heller.     Essentials  of  Materia  Medica,  Pharmacy,  and  Prescription 
Writing. 

By  Edwin  A.  Heller,  m.d.,  Quiz-Master  in  Materia  Medica  and  Pharmacy  at  the 
Medical  Institute,  University  of  Pennsylvania.      i2mo.  Cloth,  $1.50 

Henry.     Anaemia. 

A  Practical  Treatise.  By  Fred'k  P.  Henry,  m.d.,  Physician  to  Episcopal  Hospital, 
Philadelphia.  Half  Cloth,  .50 

Heusler.     The  Terpenes. 

By  Fr.  Heusler,  ph.d.,  Privatdocent  of  Chemistry  in  the  University  at  Bonn. 
Authorized  Translation  and  Revision  by  F.  J.  Pond,  ph.d.,  Assistant  Professor  of 
Chemistry,  Pennsylvania  State  College.  Cloth,  $4.00 


22  P.   BLAKIS 'TON'S  SON  &*   CO.' S 

Hemmeter.     Diseases  of  the  Stomach.     Third  Edition. 

Their  Special  Pathology,  Diagnosis,  and  Treatment.  With  Sections  on  Anatomy, 
Analysis  of  Stomach  Contents,  Dietetics,  Surgery  of  the  Stomach,  etc.  By  John  C. 
Hemmeter,  m.d.,  philos.d.,  Professor  in  the  Medical  Department  of  the  University 
of  Maryland  ;  Consultant  to  the  University  Hospital  ;  Director  of  the  Clinical  Labor- 
atory, etc. ;  formerly  Clinical  Professor  of  Medicine  at  the  Baltimore  Medical  College, 
etc.  Third  Edition,  Revised.  With  15  Plates  and  41  other  Illustrations,  some  of 
which  are  in  Colors.  Cloth,  $6.00;  Leather,  $7.00;  Half  Russia,  $8.00 

Diseases  of  the  Intestines. 

A  Complete  Systematic  Treatise  on  Diseases  of  the  Intestines,  including  their 
Special  Pathology,  Diagnosis,  and  Treatment,  with  Sections  on  Anatomy  and 
Physiology,  Microscopic  and  Chemic  Examination  of  the  Intestinal  Contents, 
Secretions,  Feces,  and  Urine.  Intestinal  Bacteria  and  Parasites  ;  Surgery  of  the 
Intestines  ;  Dietetics,  Diseases  of  the  Rectum,  etc.  With  many  Full-page  Plates, 
Colored  and  other  Illustrations,  most  of  which  are  Original.  2  vols.  Octavo. 
Just  Ready.  Vol.   I.     Cloth,  $5.00;  Sheep,  $6.00 

Vol.  II.     Cloth,  $5.00;  Sheep,  $6.00 

The  Section  on  Anatomy  has  been  prepared  by  Dr.  J.  Holmes  Smith,  Associate 
Professor  and  Demonstrator  of  Anatomy,  and  Lecturer  on  Clinical  Surgery,  University 
of  Maryland,  Baltimore.  The  Section  on  Bacteria  of  the  Intestines  has  been 
prepared  by  Dr.  Wm.  Royal  Stokes,  Associate  Professor  of  Pathology  and  Bacteriology, 
and  Visiting  Pathologist  to  the  University  Hospital,  University  of  Maryland,  Baltimore. 
The  Section  on  Diseases  of  the  Rectum  has  been  prepared  by  Dr.  Thomas  C. 
Martin,  Professor  of  Proctology,  Cleveland  College  of  Physicians  and  Surgeons.  The 
Section  on  Examination  of  Urine  and  Feces  has  been  prepared  by  Dr.  Harry 
Adler,  Demonstrator  of  Clinical  Pathology,  Associate  Professor  of  Diseases  of  the 
Stomach  and  Intestines,  University  of  Maryland,  Baltimore.  The  ILLUSTRATIONS  form 
a  most  useful  and  practical  series  of  pictures.^nearly  all  have  been  reproduced  from 
pathological  preparations  and  original  drawings,  a  few  being  printed  in  several  colors. 

Hewlett.     Manual  of  Bacteriology.     75  Illustrations. 

By  R.  T.  Hewlett,  m.d.,  m.r.c.p.,  Assistant  Bacteriologist  British  Institute  of  Pre- 
ventive Medicine,  etc.     Second  Edition,  Revised.     Just  Ready.  Cloth,  #4.00 

Hollopeter.     Hay  Fever  and  Its  Successful  Treatment. 

By  W.  C.  Hollopeter,  a.m.,  m.d.,  Clinical  Professor  of  Pediatrics  in  the  Medico- 
Chirurgical  College  of  Philadelphia  ;  Physician  to  the  Methodist  Episcopal,  Medico- 
Chirurgical,  and  St.  Joseph's  Hospitals,  etc.     Second  Edition.     i2mo.       Cloth,  $1.00 

Holden's  Anatomy.     Seventh  Edition. 

A  Manual  of  the  Dissections  of  the  Human  Body.  By  John  Langton,  f.r.c.S., 
Surgeon  to,  and  Lecturer  on  Anatomy  at,  St.  Bartholomew's  Hospital.  Carefully 
Revised  by  A.  Hewson,  m.d.,  Demonstrator  of  Anatomy,  Jefferson  Medical  College, 
Philadelphia,  etc.      320  Illustrations.     Two  small  compact  volumes.      121110. 

Vol.    I.     Scalp,  Face,  Orbit,  Neck,  Throat,  Thorax,  Upper  Extremity.     435  pages. 

153  Illustrations.  Oil  Cloth,  $1.50 

Vol.  II.     Abdomen,    Perineum,    Lower    Extremity,    Brain,   Eye,    Ear,    Mammary 

Gland,  Scrotum,  Testes.     445  pages.      167  Illustrations. 

Oil  Cloth,  $1.50 

Human  Osteology. 

Comprising  a  Description  of  the  Bones,  with  Colored  Delineations  of  the  Attach- 
ments of  the  Muscles.  The  General  and  Microscopical  Structure  of  Bone  and 
its  Development.  Eighth  Edition,  Carefully  Revised.  Edited  by  Charles 
Stewart,  f.r.s.,  and  R.  W.  Reid,  m.d.,  f.r.c.S.  With  Colored  Lithographic 
Plates  and  Numerous  Illustrations.  Cloth,  #5.25 

Landmarks. 

Medical  and  Surgical.     Fourth  Edition.      8vo.  Cloth,  .75 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  23 

Holland.     The  Urine,  the  Gastric  Contents,  the  Common  Poisons, 
and  the  Milk.     Illustrated. 

Memoranda  (Chemical  and  Microscopical)  for  Laboratory  Use.  By  J.  \V.  Holland, 
m.d.,  Professor  of  Medical  Chemistry  and  Toxicology  in  Jefferson  Medical  College 
of  Philadelphia.     Sixth  Edition,  Enlarged.     Illustrated  and  Interleaved.      i2mo. 

Horwitz's  Compend  of  Surgery.  cloth-  $I-°° 

Including  Minor  Surgery,  Amputations,  Bandaging,  Fractures,  Dislocations,  Surgical 
Diseases,  etc.,  with  Differential  Diagnosis  and  Treatment.  By  Orville  Horwitz, 
b.s.,  m.d.,  Professor  of  Genito-Urinary  Diseases,  late  Demonstrator  of  Surgery, 
Jefferson  Medical  College.  Fifth  Edition.  167  Illustrations  and  98  Formulae.  i2mo. 
No.  9  ? Quiz- Compend?  Series.  Cloth,  .80;  Interleaved  for  Notes,  $1.00 

*3.*  A  Spanish  translation  of  this  book  has  rece7itly  bee7i  published  i?i  Barcelona. 

Horsley.     The  Brain  and  Spinal  Cord, 
the  Structure  and  Functions  of.     By  Victor  A.   Horsley,  m.b.,  f.r.s.,  etc.,  As- 
sistant Surgeon  University  College  Hospital,  London,  etc.     Illustrated.     Cloth,  $2.50 

Hovell.     Diseases  of  the  Ear  and  Naso-Pharynx. 

A  Treatise  including  Anatomy  and  Physiology  of  the  Organ,  together  with  the  treat- 
ment of  the  affections  of  the  Nose  and  Pharynx  which  conduce  to  aural  disease.  By 
T.  Mark  Hovell,  f.r.c.s.  (Edin.),  m.r.c.s.  (Eng.),  Aural  Surgeon  to  the  London 
Hospital  for  Diseases  of  the  Throat,  etc.      128  Illus.     Second  Edition.     Cloth,  $5.50 

Humphrey.     A  Manual  for  Nurses.     Twenty-fourth  Edition. 

Including  General  Anatomy  and  Physiology,  Management  of  the  Sick-room,  etc.  By 
Laurence  Humphrey,  m.a.,  m.b.,  m.r.c.s.,  Assistant  Physician  to  Addenbrook's 
Hospital,  Cambridge,  England.     23d  Edition.     i2mo.     79  Illustrations.     Cloth,  $1.00 

Hughes  and  Keith.     Dissections.     Illustrated. 

A  Manual  of  Dissections  by  Alfred  W.  Hughes,  m.b.,  m.r.c.s.  (Edin.),  late  Pro- 
fessor of  Anatomy  and  Dean  of  Medical  Faculty,  King's  College,  London,  etc.,  and 
Arthur  Keith,  m.d.,  Lecturer  on  Anatomy,  London  Hospital  Medical  College,  etc. 
In  three  parts,  with  many  Colored  and  other  Illustrations. 

I.  Upper  and  Lower  Extremity.    38  Plates,  116  other  Illustrations.     Just  Ready. 

Cloth,  $3.00 
II.  Abdomen.     Thorax.     4  Plates,  149  other  Illus.     Just  Ready.        Cloth,  $3.00 
III.   Head,  Neck,  and  Central  Nervous  System.      16  Plates  and  204  other  Illustra- 
tions.    Just  Ready.  Cloth,  $3.00 

Hughes.     Compend  of  the  Practice  of  Medicine.     Sixth  Edition. 

Giving  the  Synonyms,  Definition,  Causes,  Symptoms,  Pathology,  Prognosis,  Diag- 
nosis, Treatment,  etc.,  of  each  Disease.  The  Treatment  is  especially  full  and  a 
number  of  valuable  Prescriptions  have  been  incorporated.  Sixth  Edition,  Revised 
and  Enlarged.  By  Daniel  E.  Hughes,  m.d.,  Chief  Resident  Physician  Philadel- 
phia Hospital ;  formerly  Demonstrator  of  Clinical  Medicine  at  Jefferson  Medical 
College,  Philadelphia.     Being  Nos.  2  and  3  f  Quiz-  Compend  ?  Series. 

Quiz-Compend  Edition,  in  two  Parts. 

Part  I. — Continued,  Eruptive,  and  Periodical  Fevers,  Diseases  of  the  Mouth, 
Stomach,  Intestines,  Peritoneum,  Biliary  Passages,  Liver,  Kidneys,  Blood,  etc., 
Parasites,  etc.,  and  General  Diseases,  etc. 

Part  II. — Physical  Diagnosis,  Diseases  of  the  Respiratory  System,  Circulatory 
System,  Diseases  of  the  Brain  and  Nervous  System,  Mental  Diseases,  etc. 

Price  of  each  Part,  in  Cloth,  .80  ;  Interleaved  for  the  Addition  of  Notes,  $1.00 

Physicians'  Edition. 

In  one  volume,  including  the  above  two  parts,  a  Section  on  Skin  Diseases,  and 
an  Index.     Sixth  Revised  and  Enlarged  Edition.     625  pages. 

Full  Morocco,  Gilt  Edges,  Round  Corners,  $2.25 


24  P.  BLAKISTON'S  SON  6-    CO.'S 

Ireland.     The  Mental  Affections  of  Children. 

Idiocy,  Imbecility,  Insanity,  etc.  By  W.  W.  Ireland,  m.d.  (Edin.),  of  the  Home 
and  School  for  Imbeciles,  Mavisbush,  Scotland  ;  Second  Edition,  Revised  and  En- 
larged. Cloth,  $4.00 

Jacoby.     Electrotherapy.      Illustrated. 

See  Cohen,  Physiologic  Therapeutics,  page  9. 

Jacobson.     The  Operations  of  Surgery. 

By  W.  H.  A.  Jacobson,  f.r.cs.  (Eng.),  Surgeon  Guy's  Hospital,  etc.,  and  F.  J. 
Steward,  f.r.cs.,  Assistant  Surgeon  Guy's  Hospital  and  the  Hospital  for  Sick  Chil- 
dren, Great  Ormand  Street,  London.  With  550  Illustrations.  Fourth  Edition, 
Revised  and  Enlarged.     Two  volumes.     Octavo.      1524  pages. 

Cloth,  $10.00  ;  Leather,  $12.00 

Jennings.     A  Manual  of  Ophthalmoscopy. 

By  J.  E.  Jennings,  m.d.  (Univ.  Penna.),  Formerly  Clinical  Assistant  Royal  London 
Ophthalmic  Hospital,  London  ;  Fellow  of  the  British  Laryngological  and  Rhinological 
Association  ;  Member  of  the  American  Medical  Association  ;  Member  of  the  St. 
Louis  Medical  Society,  etc.     With  95  Illustrations  and  1  Colored  Plate.    Just  Ready. 

Cloth,  $1.50 

Jones.      Medical  Electricity.     Third  Edition. 

A  Practical  Handbook  for  Students  and  Practitioners  of  Medicine.  By  H.  Lewis 
Jones,  m.a.,  m.d.,  f.r.cp.,  Medical  Officer  in  Charge  Electrical  Department,  St. 
Bartholomew's  Hospital.  Third  Edition  of  Steavenson  and  Jones'  Medical  Elec- 
tricity, Revised  and  Enlarged.      1 17  Illustrations.      532  pages.      i2mo.     Cloth,  $3.00 

Jones.     Outlines  of  Physiology. 

By  Edward  Groves  Jones,  m.d.,  Assistant  Professor  of  Physiology  and  Pathological 
Anatomy,  Atlanta  College  of  Physicians    and    Surgeons.     96  Illustrations.      i2mo. 

Cloth,  $1.50 

Keay.     Gall-Stones. 

The  Medical  Treatment  of  Gall-Stones.  By  J.  H.  Keay,  m.a.,  m.d.,  Physician  to 
Trinity  Hospital,  Greenwich,  London.      121110.  Cloth,  $1.25 

Keen.     Clinical  Charts. 

A  Series  of  Seven  Outline  Drawings  of  the  Human  Body,  on  which  may  be  marked 
the  course  of  any  Disease,  Fractures,  Operations,  etc.  By  W.  W.  Keen,  m.d., 
Professor  of  the  Principles  of  Surgery  and  Clinical  Surgery,  Jefferson  Medical  College. 
Each  Drawing  may  be  had  separately  gummed  on  back  for  pasting  in  case  book. 
25  to  the  pad.    Price,  25  cents.    Special  Charts  will  be  printed  to  order.    Samples  free. 

Kehr.      Diagnosis  of  Gail-Stone  Disease. 

Including  one  hundred  Clinical  and  Operative  Cases  illustrating  Diagnostic  Points  of 
the  Different  Forms  of  the  Disease.  By  Prof.  Dr.  Hans  Kehr,  of  Halberstadt. 
Authorized  Translation  by  William  Wotkvns  Seymour,  a.u.  (Yale),  m.d.  (Harvard), 
of  Troy,  N.  Y.      i2mo.      370  pages.  Cloth,  $2.50 

Kenwood.      Public  Health  Laboratory  Work. 

By  H.  R.  KENWOOD,  M.B.,  D.P.H.,  F.C.S.,  Assistant  Professor  of  Public  Health, 
University  College,  London,  etc.      116  Illustrations  and  3  Plates.  Cloth,  $2.00 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  25 

Kirkes'  Physiology.     Seventeenth  Edition. 

{The  only  Authorized  Edition.  i2mo.  Dark  Red  Cloth. .)  A  Handbook  of  Physiology. 
Seventeenth  London  Edition,  Revised  and  Enlarged.  By  W.  D.  Halliburton,  m.d., 
f.r.s.,  Professor  of  Physiology,  King's  College,  London.  Thoroughly  Revised  and 
in  many  parts  Rewritten.  68 1  Illustrations,  a  number  of  which  are  printed  in  Colors. 
888  pages.      i2mo.  Cloth,  $3.00  ;  Leather,  $3.75 

IMPORTANT   NOTICE.     This  is  the  identical  Edition  of  "  Kirkes'  Physiology,"  as  published  in 

London  by  John  Murray,  the  sole  owner  of  the  book,  and  containing 

the  revisions  and  additions  of  Dr.  Halliburton,  and  the  new  and  original  illustrations  included  at 
his  suggestion.     This  edition  has  been  carefully  and  thoroughly  revised. 

Kleen.     Diabetes  Mellitus  and  Glycosuria. 

Their  Diagnosis  and  Treatment.     By  Dr.  Emil  Kleen.     Octavo.  Cloth,   $2.50 

Knight.     Diseases  of  the  Throat. 

A  Manual  for  Students.  By  Charles  H.  Knight,  m.d.,  Professor  of  Laryngology, 
Cornell  University  Medical  College  ;  Surgeon  to  Throat  Department,  Manhattan  Eye 
and  Ear  Hospital,  etc.     Illustrated.  Nearly  Ready. 

Knopf.     Pulmonary  Tuberculosis.     Its  Modern  Prophylaxis  and  the 
Treatment  in  Special  Institutions  and  at  Home. 

By  S.  A.  Knopf,  m.d.,  Physician  to  the  Lung  Department  of  the  New  York  Throat 
and  Nose  Hospital  ;  former  Assistant  Physician  to  Professor  Dettweiler,  Falkenstein 
Sanatorium,  Germany,  etc.      Illustrated.     Octavo.  Cloth,  $3.00 

Kyle.     Diseases  of  the  Ear,  Nose,  and  Throat. 

A  Compend  for  Students  and  Physicians.     By  John  J.  Kyle,  m.d.     Illus.     In  Press. 

Landis'  Compend  of  Obstetrics. 

By  Henry  G.   Landis,  m.d.     Seventh  Edition,  Revised  by  Wm.  H.  Wells,  m.d., 

Demonstrator  of  Clinical     Obstetrics,  Jefferson  Medical  College  ;  Member  Obstetrical 

Society  of  Philadelphia,  etc.     With  52  Illustrations.     No.  j  ?  Quiz-  Compend ?  Series. 

Cloth,  .80  ;  Interleaved  for  the  Addition  of  Notes,  $1.00 

Landois.     A  Text-Book  of  Human  Physiology. 

Including  Histology  and  Microscopical  Anatomy,  with  Special  Reference  to  the  Re- 
quirements of  Practical  Medicine.  By  Dr.  L.  Landois,  Professor  of  Physiology  and 
Director  of  the  Physiological  Institute  in  the  University  of  Greifswald.  Fifth  Ameri- 
can translated  from  the  last  German  Edition,  with  Additions,  by  Wm.  Stirling, 
m.d.,  D.Sc,  Brackenbury  Professor  of  Physiology  and  Histology  in  Owens  College, 
and  Professor  in  Victoria  University,  Manchester.  With  845  Illustrations,  many  of 
which  are  printed  in  Colors.     8vo.  In  Press. 

Lazarus-Barlow.     Pathological  Anatomy  and  Histology. 

By  W.  S.  Lazarus-Barlow,  m.d.,  Demonstrator  of  Pathology  at  the  University  of 
Cambridge,  England.  With  7  Colored  Plates  containing  19  figures  and  171  other 
Illustrations.     Octavo.  Cloth,  $6.50 

Lee.     The  Microtomist's  Vade  Mecum.     Fifth  Edition. 

A  Handbook  of  the  Methods  of  Microscopic  Anatomy.  By  Arthur  Bolles  Lee, 
formerly  Assistant  in  the  Russian  Laboratory  of  Zoology  at  Villefranche-sur-Mer  (Nice). 
894  Articles.     Enlarged,  Revised,  and  Rearranged.      532  pages.     8vo.     Cloth,  $4.00 

Leffmann  and  Beam.      Food  Analysis.     Illustrated. 

Select  Methods  in  Food  Analysis.  By  Henry  Leffmann,  m.d.,  Professor  of  Chem- 
istry in  the  Woman's  Medical  College  of  Pennsylvania  and  in  the  Wagner  Free 
Institute  of  Science  ;  Pathological  Chemist,  Jefferson  Medical  College  Hospital,  Phila- 
delphia ;  Vice-President  (190 1 )  Society  Public  Analysts,  etc.;  and  William  Beam, 
a.m.     With  many  Tables,  4  Plates  and  53  other  Illustrations.      121110.     Cloth,  $2.50 


26  P.  BLAKISTON'S  SON  <S-    CO.' S 

Leffmann.     Compend  of  Medical  Chemistry. 

Inorganic  and  Organic.  Including  Urine  Analysis.  By  Henry  Leffmann,  m.d., 
Professor  of  Chemistry  in  the  Woman's  Medical  College  of  Pennsylvania  and  in  the 
Wagner  Free  Institute  of  Science,  Philadelphia  ;  Pathological  Chemist  Jefferson  Medi- 
cal College  Hospital,  etc.    No.  10  ? Quiz- Compend  ?  Series.    Fourth  Edition,  Rewritten. 

Cloth,  .80  ;  Interleaved  for  the  Addition  of  Notes,  $1.00 

The  Coal-Tar  Colors. 

With  Special  Reference  to  their  Injurious  Qualities  and  the  Restrictions  of  their 
Use.     A  Translation  of  Theodore  Weyl's  Monograph.      i2mo.  Cloth,  $1.25 

Examination  of  Water 

for  Sanitary  and  Technical  Purposes.  Fourth  Edition,  Enlarged.  Illustrated. 
i2mo.  Cloth,  $1.25 

Analysis  of  Milk  and  Milk  Products. 

Arranged  to  suit  the  needs  of  Analytical  Chemists,  Dairymen,  and  Milk  Inspec- 
tors.    Second  Edition,  Revised  and  Enlarged.     Illustrated.     i2mo.     Cloth,  $1.25 

Handbook  of  Structural  Formulae 

for  the  Use  of  Students,  containing  1 80  Structural  and  Stereo-chemic  Formulae. 
i2mo.      Interleaved.  Cloth,  $1.00 

Lewers.     On  the  Diseases  of  Women. 

A  Practical  Treatise.  By  Dr.  A.  H.  N.  Lewers,  Obstetric  Physician  to  the  London 
Hospital.      146  Engravings.     Fifth  Edition,  Revised.  Cloth,  $2.50 

Cancer  of  the  Uterus. 

A  Clinical  Monograph  on  its  Diagnosis  and  Treatment,  with  the  After-Results 
in  Seventy-three  Cases  Treated  by  Radical  Operation.  With  51  Original  Illus- 
trations and  3  Colored  Plates.     8vo.      328  pages.  Cloth,  $3.00 

Lewis  (Bevan).     Mental  Diseases. 

A  Text-Book  having  Special  Reference  to  the  Pathological  Aspects  of  Insanity.  By 
Bevan  Lewis,  l.r.c.p.,  m.r.c.s.,  Medical  Director  West  Riding  Asylum,  Wake- 
field, England.  26  Lithograph  Plates  and  other  Illustrations.  Second  Edition,  Re- 
vised and  Enlarged.     8vo.  Cloth,  $7.00 

Lincoln.     School  and  Industrial  Hygiene. 
By  D.  F.  Lincoln,  m.d.  Cloth,  .40 

Longley's  Pocket  Medical  Dictionary. 

Giving  the  Definition  and  Pronunciation  of  Words  and  Terms  in  General  Use  in 
Medicine.  With  an  Appendix,  containing  Poisons  and  their  Antidotes,  Abbreviations 
Used  in  Prescriptions,  etc.   By  Elias  Longley.   Cloth,  .75  ;  Tucks  and  Pocket,  #1.00 

Macalister's  Human  Anatomy.      816  Illustrations. 

Systematic  and  Topographical,  including  the  Embryology,  Histology,  and  Mor- 
phology of  Man.  With  Special  Reference  to  the  Requirements  of  Practical  Surgery 
and  Medicine.  By  Alex.  Macalister,  m.d.,  f.r.S.,  Professor  of  Anatomy  in  the 
University  of  Cambridge.     816  Illustrations.     Octavo.     Cloth,  #5.00;  Leather,  #6.00 

MacLeod.     Practical  Handbook  of  the  Pathology  of  the  Skin. 

An  Introduction  to  the  Histology,  Pathology,  and  Bacteriology  of  the  Skin,  with 
special  reference  to  Technique.  By  J.  M.  H.  MacLeod,  m.a.,  m.d.,  m.r.c.p., 
Assistant  in  the  Dermatological  Department,  Charing  Cross  Hospital  ;  Physician  to 
the  Skin  Department,  Victoria  Hospital  for  Children.  With  8  Colored  and  32  Black 
and  White  Plates.     Octavo.     Just  Ready.  Cloth,  #5.00 

Mc Bride.      Diseases  of  the  Throat,  Nose,  and  F,ar. 

A  Clinical  Manual  for  Students  and  Practitioners.  By  P.  McBride,  m.d.,  f.r.c.p. 
(Edin.)  ;  Lecturer  on  Diseases  of  Throat  and  Ear,  Edinburgh  School  of  Medicine, 
etc.  With  Colored  Illustrations  from  Original  Drawings.  Third  Edition,  Revised 
and  Enlarged.     Octavo.  Cloth,  Gilt  Top,  #7.00 


MEDICAL   AND   SCIENTIFIC  PUBLICATIONS.  27 

McCook.     American  Spiders  and  Their  Spinning  Work. 

A  Natural  History  of  the  Orbweaving  Spiders  of  the  United  States.  By  Henry  C. 
McCook,  d.d.,  Vice-President  of  the  Academy  of  Natural  Sciences  of  Philadelphia, 
etc.     Three  volumes.     Handsomely  Illustrated  in  Colors.  Cloth,  $40.00 

Macready.     A  Treatise  on  Ruptures. 

By  Jonathan  F.  C.  H.  Macready,  f.r.c.s.,  Surgeon  to  the  Great  Northern  Central 
Hospital ;  to  the  City  of  London  Hospital  for  Diseases  of  the  Chest,  etc.  24  Full- 
page  Plates  and  Wood  Engravings.     Octavo.  Cloth,  $6.00 

McFarland.     Prophylaxis — Personal  Hygiene — Nursing  and  Care  of 
the  Sick. 
See  Cohen,  Physiologic  Therapeutics,  page  10. 

McMurrich.     The  Development  of  the  Human  Body. 

A  Manual  of  Human  Embryology.  By  J.  Playfair  McMurrich,  a.m.,  ph.d., 
Professor  of  Anatomy,  Medical  Department  of  the  University  of  Michigan,  Ann  Arbor. 
276  Illustrations.  Cloth,  $3.00 

Makins.     Surgical  Experiences  in  South  Africa,  1 899-1 900. 

Being  mainly  a  Clinical  Study  of  the  Effects  of  Injuries  Produced  by  Bullets  of  Small 
Calibre.  By  George  Henry  Makins,  f.r.c.s.,  Surgeon  to  St.  Thomas's  Hospital, 
London  ;  and  late  one  of  the  Consulting  Surgeons  to  the  South  African  Field  Force. 
With  25  Plates  and  96  other  Illustrations.     Octavo.  Cloth,  $4.00 

Mann.     Forensic  Medicine  and  Toxicology. 

By  J.  Dixon  Mann,  m.d.,  f.r.cp.,  Professor  of  Medical  Jurisprudence  and  Toxi- 
cology in  Owens  College,  Manchester,  etc.     Illustrated.     Octavo.  Cloth,  $6. 50 

Mann's  Manual  of  Psychological  Medicine 

and  Allied  Nervous  Diseases.  Their  Diagnosis,  Pathology,  Prognosis,  and  Treat- 
ment, including  their  Medico-Legal  Aspects.  With  Chapter  on  Expert  Testimony  and 
an  Abstract  of  the  Laws  Relating  to  the  Insane  in  all  the  States  of  the  Union.  By 
Edward  C.  Mann,  m.d.     With  Illustrations.     Octavo.  Cloth,  $3.00 

Marshall's  Physiological  Diagrams,  Life  Size,  Colored. 

Eleven  Life-size  Diagrams  (each  7  feet  by  3  feet  7  inches).  Designed  for  Demon- 
stration before  the  Class.  By  John  Marshall,  f.r.s.,  f.r.c.s.,  Professor  of 
Anatomy  to  the  Royal  Academy  ;  Professor  of  Surgery,  University  College,  London, 
etc.  In  Sheets,  $40.00  ;  Backed  with  Muslin  and  Mounted  on  Rollers,  $60.00 

Ditto,  Spring  Rollers,  in  Handsome  Walnut  Map  Case,  $100.00 
Single  Plates,  Sheets,  $5.00;  Mounted,  $7.50;  Explanatory  Key,  50  cents. 

Purchaser  inust  pay  freight  charges. 

No.  1 — The  Skeleton  and  Ligaments.  No.  2 — The  Muscles  and  Joints,  with  Ani- 
mal Mechanics.  No.  3 — The  Viscera  in  Position.  No.  4 — The  Heart  and  Principal 
Blood-vessels.  No.  5 — The  Lymphatics.  No.  6 — The  Digestive  Organs.  No.  7 — The 
Brain  and  Nerves.  Nos.  8  and  9 — The  Organs  of  the  Senses.  Nos.  10  and  11 — The 
Microscopic  Structure  of  the  Textures  and  Organs.     (Send  for  Special  Circular.) 

Maxwell.     Terminologia  Medica  Polyglotta. 
By  Dr.  Theodore  Maxwell.     Octavo.  Cloth,  $3.00 

The  object  of  this  work  is  to  assist  the  medical  men  of  any  nationality  in  reading  medical 
literature  written  in  a  language  not  their  own.  Each  term  is  usually  given  in  seven  languages, 
viz.  :   English,  French,  German,  Italian,  Spanish,  Russian,  and  Latin. 


28  P.  BLAKISTON'S  SON  &-    CO.' S 

Maylard.     The  Surgery  of  the  Alimentary  Canal. 

By  Alfred  Ernest  Maylard,  m.b.,  b.s.,  Senior  Surgeon  to  the  Victoria  Infirmary, 
Glasgow.     Second  Edition.     97  Illustrations.     Octavo.  Cloth,  $3.00 

Mays'  Theine  in  the  Treatment  of  Neuralgia. 
By  Thomas  J.  Mays,  m.d.     i6mo.  yz  bound,  .50 

Memminger.     Diagnosis  by  the  Urine. 

The  Practical  Examination  of  Urine,  with  Special  Reference  to  Diagnosis.  By 
Allard  Memminger,  m.d.,  Professor  of  Chemistry  and  Hygiene  ;  Clinical  Professor 
of  Urinary  Diagnosis  in  the  Medical  College  of  the  State  of  South  Carolina  ;  Visiting 
Physician  in  the  City  Hospital  of  Charleston,  etc.  Second  Edition,  Enlarged  and 
Revised.     24  Illustrations.      i2mo.  Cloth,  $1.00 

Minot.     Embryology. 

A  Laboratory  Text-Book  of  Embryology.  By  Charles  S.  Minot,  s.d.,  ll.d.,  Pro- 
fessor of  Histology  and  Human  Embryology,  Harvard  University  Medical  School. 
Illustrated.  Cloth,  $4.50 

Montgomery.     A  Text-Book  of  Practical  Gynecology. 
By  Edward  E.  Montgomery,  m.d.,  Professor  of  Gynecology  in  Jefferson  Medical 
College,  Philadelphia  ;  Gynecologist  to  the  Jefferson  and  St.  Joseph's  Hospitals,  etc. 
527  Illustrations,  many  of  which    are  from  original  sources.     800  pages.     Octavo. 

Cloth,  #5.00  ;  Leather,  #6.00 

"  The  author  has  a  clear  conception  of  his  subject  ;  this,  wiih  his  manner  of  treatment,  intro- 
duces the  reader  to  questions  otherwise  intricate  in  such  a  manner  as  to  make  them  easily  compre- 
hended. His  introduction,  together  with  his  comments  on  diagnosis  and  examination  of  the 
patient  are  delightfully  clear  and  instructive.  Therapeutics,  local  and  systematic,  are  clearly  and 
intelligently  discussed." — Brooklyn  Medical  Journal. 

Morris.  Text-Book  of  Anatomy.  Third  Edition.  846  Illustra- 
tions, 267  in  Colors. 
A  Complete  Text-Book.  Edited  by  Henry  Morris,  f.r.c.s.,  Surgeon  to,  and  Lec- 
turer on  Anatomy  at,  Middlesex  Hospital,  assisted  by  Peter  Thompson,  m.d., 
J.  Bland  Sutton,  f.r.c.s.,  J.  H.  Davies-Colley,  f.r.c.s.,  Wm.  J.  Walsham, 
f.r.c.s.,  H.  St.  John  Brooks,  m.d.,  R.  Marcus  Gunn,  f.r.c.s.,  Arthur  Hensman, 
f.r.c.s.,  Frederick  Treves,  f.r.c.s.,  William  Anderson,  f.r.c.s.,  Arthur  Rob- 
inson, m.d.,  m.r.c.s.,  and  Prof.  W.  H.  A.  Jacobson.  One  Handsome  Octavo 
Volume,  with  846  Illustrations,  of  which  267  are  printed  in  Colors.  Thumb  Index  and 
Colored  Illustrations  in  all  Copies.     Cloth,  $6.00  ;  Leather,  $7.00  ;  Half  Russia,  $8.00 

"Of  all  the  text-books  of  moderate  size  on  human  anatomy  in  the  English  language,  Morris 
is  undoubtedly  the  most  up-to-date  and  accurate.  .  .  .  For  the  student,  the  surgeon,  or  for  the 
general  practiiioner  who  desires  to  review  his  anatomy,  Morris  is  decidedly  the  book  to  buy." — 
The  Thiladelphia  Medical  Journal. 

*#*  Morris'  Anatomy  is  now  the  recognized  standard  text-book  in  a  large  number 
of  medical  schools  throughout  the  United  States,  England,  and  Canada.  It  is  in  many 
respects  the  best  book  for  students'  use,  and  in  its  present  edition  is  the  latest  and  best 
illustrated  of  all  books  on  anatomy.  The  revisions  have  been  carefully  made  and 
edited,  several  sections  having  been  almost  entirely  rewritten,  old  illustrations  replaced 
and  new  ones  added,  a  larger  number  being  printed  in  colors. 

Renal  Surgery. 

With  Special  Reference  to  Stone  in  the  Kidney  and  Ureter,  and  to  the  Surgical 
Treatment  of  Calculous  Anuria,  together  with  a  Critical  Examination  of  Sub- 
parietal  Injuries  of  the  Ureter.      Illustrated.      8vo.  Cloth,  #2.00 

Mitchell  and  Gulick.      Mechanotherapy. 
See  Cohen,  Physiologic  Therapeutics,  page  10. 


MEDICAL   AND   SCIENTIFIC  PUBLICATIONS.  29 

Morton  on  Refraction  of  the  Eye. 

Its  Diagnosis  and  the  Correction  of  its  Errors.     With  Chapter  on  Keratoscopy  and 
Test  Types.     By  A.  Morton,  m.b.     Sixth  Edition,  Revised.  Cloth,  $1.00 

Moullin.  Surgery.  Third  Edition,  by  Hamilton. 
A  Complete  Text-Book.  By  C.  W.  Mansell  Moullin,  m.a.,  m.d.  (Oxon.),  f.r.c.s., 
Surgeon  and  Lecturer  on  Physiology  to  the  London  Hospital ;  formerly  Radcliffe 
Traveling  Fellow  and  Fellow  of  Pembroke  College,  Oxford.  Third  American 
Edition,  Revised  and  Edited  by  the  late  John  B.  Hamilton,  m.d.,  ll.d.,  Professor 
of  the  Principles  of  Surgery  and  Clinical  Surgery,  Rush  Medical  College,  Chicago  ; 
Professor  of  Surgery,  Chicago  Polyclinic  ;  Surgeon,  formerly  Supervising  Surgeon- 
General,  U.  S.  Marine  Hospital  Service  ;  Surgeon  to  Presbyterian  Hospital.  600 
Illustrations,  over  200  of  which  are  original,  and  many  of  which  are  printed  in 
Colors.     Octavo.      1250  pages.     Cloth,  $6.00;  Leather,  $7.00;  Half  Russia,  $8.00 

Enlargement  of  the  Prostate. 

Its    Treatment   and    Radical    Cure.     Illustrated.     Second    Edition,    Enlarged. 
Octavo.  Cloth,  $1.75 

Inflammation  of  the  Bladder  and  Urinary  Fever. 

Octavo.  Cloth,  $1.50 

Murray.     Rough  Notes  on  Remedies. 

By  Wm.  Murray,  m.d.,  f.r.c.p.  (Lond.),  Consulting  Physician  Newcastle-on-Tyne 
Hospital  for  Sick  Children.     Fourth  Edition,  Enlarged.     Crown  8vo.     Cloth,  $1.25 

Muter.     Practical  and  Analytical  Chemistry. 
By  John  Muter,  f.r.s.,   f.c.s.,  etc.     Second  American  from  the  Eighth  English 
Edition.     Revised  to  meet  the  Requirements   of  American  Medical  and   Pharma- 
ceutical Colleges.      56  Illustrations.  Cloth,  $1.25 

New  Sydenham  Society  Publications. 

From  three  to  six  volumes  published  each  year.     List  of  Volumes  upon  application. 

Per  annum,  $8.00 

Notter.     The  Theory  and  Practice  of  Hygiene.     Second  Edition. 

A  Complete  Treatise  by  J.  Lane  Notter,  m.a.,  m.d.,  f.c.s.,  Fellow  and  Member 
of  Council  of  the  Sanitary  Institute  of  Great  Britain  ;  Professor  of  Hygiene,  Army 
Medical  School ;  Examiner  in  Hygiene,  University  of  Cambridge,  etc. ;  and  W.  H. 
Horrocks,  m.d.,  B.  Sc.  (Lond.),  Assistant  Professor  of  Hygiene,  Army  Medical 
School,  Netley.  Illustrated  by  15  Lithographic  Plates  and  138  other  Illustrations, 
and  including  many  Useful  Tables.  Second  Edition,  Carefully  Revised.  Octavo. 
1085  pages.  Cloth,  $7.00 

Oertel.     Medical  Microscopy. 

A  Guide  to  Diagnosis,  Elementary  Laboratory  Methods,  and  Microscopic  Technic. 
By  T.  E.  Oertel,  m.d.,  Professor  of  Histology,  Pathology,  Bacteriology,  and  Clinical 
Microscopy,  Medical  Department,  University  of  Georgia.     121110.      131  Illustrations. 

Cloth,  $2.00 

Oettel.     Practical  Exercises  in  Electro-Chemistry. 
By  Dr.  Felix  Oettel.     Authorized  Translation  by  Edgar  F.  Smith,  m.a.,  Professor 
of  Chemistry,  University  of  Pennsylvania.      Illustrated.  Cloth,  .75 

Introduction  to  Electro-Chemical  Experiments. 

Illustrated.     By  same  Author  and  Translator.  Cloth,  .75 


30  P.  BLAKISTON'S  SON  &-   CO.' S 

Ohlemann.     Ocular  Therapeutics  for  Physicians  and  Students. 

By  M.  Ohlemann,  m.d.,  late  Physician  in  the  Ophthalmological  Clinical  Institute, 
Royal  Prussian  University  of  Berlin,  etc.  Translated  and  Edited  by  Charles  A. 
Oliver,  a.m.  ,  m.d.  ,  Attending  Surgeon  to  the  Wills  Eye  Hospital ;  Ophthalmic  Surgeon 
to  the  Philadelphia  and  to  the  Presbyterian  Hospitals.      i2mo.  Cloth,  $1.75 

Ormerod.     Diseases  of  Nervous  System. 

By  J.  A.  Ormerod,  m.d.  (Oxon.),  f.r.c.p.,  Physician  to  National  Hospital  for  the 
Paralyzed  and  Epileptic,  London.     66  Wood  Engravings.      i2mo.  Cloth,  $1.00 

Osgood.     The  Winter  and  Its  Dangers. 
By  Hamilton  Osgood,  m.d.  Cloth,  .40 

Ostrom.     Massage  and  the  Original  Swedish  Movements. 

Their  Application  to  Various  Diseases  of  the  Body.  A  Manual  for  Students,  Nurses, 
and  Physicians.  By  Kurre  W.  Ostrom,  from  the  Royal  University  of  Upsala, 
Sweden,  Formerly  Instructor  in  Massage  and  Swedish  Movements  in  the  Hospital  of 
the  University  of  Pennsylvania  and  in  the  Philadelphia  Polyclinic  and  College  for 
Graduates  in  Medicine,  etc.  Fifth  Edition,  Enlarged.  1 1  5  Illustrations,  many  of 
which  were  drawn  especially  for  this  purpose.      i2mo.     Just  Ready.         Cloth,  $1.00 

Packard's  Sea  Air  and  Sea  Bathing. 
By  John  H.  Packard,  m.d.  Cloth,  .40 

Parkes  and  Kenwood.     Hygiene  and  Public  Health. 

A  Practical  Manual.  By  Louis  C.  Parkes,  m.d.,  d.p.h.  (Lond.  Univ.),  Lecturer 
on  Public  Health  at  St.  George's  Hospital  ;  Medical  Officer  of  Health  and  Public 
Analyst,  Borough  of  Chelsea,  London,  etc.;  and  Henry  Kenwood,  m.b.,  f.c.s., 
Assistant  Professor  of  Public  Health,  University  College,  London,  etc.  Second  Edition, 
Enlarged  and  Revised.     85  Illustrations.      i2mo.     Just  Ready.  Cloth,  #3.00 

*¥r*  Upon  the  exhaustion  of  the  fifth  edition  of  what  had  been  known  for  many 
years  as  "Parkes'  Hygiene,"  Dr.  Parkes  associated  with  himself  Prof.  Kenwood. 
The  whole  work  was  recast  and  issued  under  this  dual  authorship  as  a  new  book.  This 
edition  is  the  second  printed  under  the  new  arrangement,  but  is  really  the  seventh 
revision. 

"  The  style  is  good ;  dry  facts,  laws,  and  statistics  are  put  in  such  a  way  that  the  reader  does 
not  tire  of  them  and  yet  finds  them  easy  to  remember." — University  Medical  Magazine. 

Parsons.     Elementary  Ophthalmic  Optics. 
By  J.  Herbert  Parsons,  m.b.,  m.r.c.s.,  Clinical  Assistant,  Royal  London  Ophthal- 
mic Hospital.     With  Diagrammatic  Illustrations.     Just  Ready.  Cloth,  $2.00 

Pershing.     The  Diagnosis  of  Nervous  and  Mental  Diseases. 

By  Howell  T.  Pershing,  m.d.,  Professor  of  Nervous  and  Mental  Diseases  in  the 
University  of  Denver;  Neurologist  to  St.  Luke's  Hospital;  Consultant  in  Nervous 
and  Mental  Diseases  to  the  Arapahoe  County  Hospital  ;  Member  of  the  American 
Neurological  Association.     With  colored  and  other  Illustrations.  Cloth,  #1.25 

Phillips.     Spectacles  and  Eyeglasses. 
Their  Prescription  and  Adjustment.     By  R.  J.  Phillips,  m.d.,  late  Adjunct  Profes- 
sor of  Diseases  of  the  Eye,   Philadelphia  Polyclinic  ;   Ophthalmic  Surgeon,  Presby- 
terian Orphanage.     Third  Edition,  Revised  and  Enlarged.      52  Illustrations.      i2mo. 

Cloth,  $1.00 


MEDICAL  AND   SCIENTIFIC  PLBLICATIONS.  31 

The  Physician's  Visiting  List. 

Published  Annually.     Fifty-Second  Year  (1903)  of  its  Publication. 

Hereafter  all  styles  will  contain  the  interleaf  or  special  memoranda  page,  except 
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REGULAR    EDITION. 

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gUP  This  list  combines  the  several  essential  qualities  of  strength,  compactness, 
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application. 

Potter.     A  Handbook  of  Materia  Medica,  Pharmacy,  and  Thera- 
peutics.    Ninth  Edition,  Enlarged. 

Including  the  Action  of  Medicines,  Special  Therapeutics  of  Disease,  Official  and 
Practical  Pharmacy,  and  Minute  Directions  for  Prescription  Writing,  etc.  Including 
over  650  Prescriptions  and  Formulas.  By  SamuelO.  L.  Potter,  m.a.,  m.d.,  m.r.c.p. 
(Lond.),  formerly  Professor  of  the  Principles  and  Practice  of  Medicine,  Cooper  Medical 
College,  San  Francisco  ;  Major  and  Brigade  Surgeon,  U.  S.  Vol.  Ninth  Edition, 
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Compend  of  Anatomy,  including  Visceral  Anatomy. 

Sixth  Edition,   Revised  and  greatly  Enlarged.     With   16   Lithographed  Plates 
and  117  other  Illustrations.     Being  No.  1  fQuiz-Competid  ?  Series. 

Cloth,  .80;  Interleaved  for  Taking  Notes,  $1.00 

Compend   of    Materia   Medica,   Therapeutics,   and   Prescription 
Writing. 

With  Special  Reference  to  the  Physiological  Action  of  Drugs.     Sixth  Revised  and 
Improved  Edition,  with  Index.      Being  No.  6  ?  Quiz- Compend  f  Series. 

Cloth,  .80  ;  Interleaved  for  Taking  Notes,  $1.00 


32  P.  BLAKISTON'S  SON  &*   CO.'S 

Potter.     Speech  and  Its  Defects. 

Considered  Physiologically,  Pathologically,  and  Remedially  ;  being  the  Lea  Prize 
Thesis  of  Jefferson  Medical  College,  1882.     Revised  and  Corrected.         Cloth,  $1.00 

Power.     Surgical  Diseases  of  Children 

and  their  Treatment  by  Modern  Methods.  By  D'Arcy  Power,  m.a.,  f.r.c.s. 
(Eng.),  Demonstrator  of  Operative  Surgery,  St.  Bartholomew's  Hospital  ;  Surgeon 
to  the  Victoria  Hospital  for  Children.      Illustrated.      i2mo.  Cloth,  $2.50 

Preston.     Hysteria  and  Certain  Allied  Conditions. 

Their  Nature  and  Treatment.  With  Special  Reference  to  the  Application  of  the  Rest 
Cure,  Massage,  Electrotherapy,  Hypnotism,  etc.  By  George  J.  Preston,  m.d., 
Professor  of  Diseases  of  the  Nervous  System,  College  of  Physicians  and  Surgeons, 
Baltimore  ;  Visiting  Physician  to  the  City  Hospital  ;  Consulting  Neurologist  to  Bay 
View  Asylum  and  the  Hebrew  Hospital  ;  Member  American  Neurological  Associa- 
tion, etc.      Illustrated.      i2mo.  Cloth,  $2.00 

Pritchard.     Handbook  of  Diseases  of  the  Ear. 

By  Urban  Pritchard,  m.d.,  f.r.c.s.,  Professor  of  Aural  Surgery,  King's  College, 
London;  Aural  Surgeon  to  King's  College  Hospital;  Senior  Surgeon  to  the  Royal 
Ear  Hospital,  etc.     Fourth  Edition.     Many  Illustrations  and  Formulae.  In  Press. 

Proctor's  Practical  Pharmacy. 

Lectures  on  Practical  Pharmacy.  By  Barnard  S.  Proctor.  Third  Edition,  Re- 
vised.   With  Elaborate  Tables  of  Chemical  Solubilities,  etc.     Illustrated.    Cloth,  $3.00 

Reese's  Medical  Jurisprudence  and  Toxicology. 

A  Text-Boo^  for  Medical  and  Legal  Practitioners  and  Students.  By  John  J.  Reese, 
m.d.,  Editor  of  "Taylor's  Jurisprudence,"  formerly  Professor  of  the  Principles  and 
Practice  of  Medical  Jurisprudence,  including  Toxicology,  in  the  University  of  Pennsyl- 
vania Medical  Department.  Sixth  Edition,  Revised  and  Edited  by  Henry  Leffmann, 
m.d.,  Pathological  Chemist,  Jefferson  Medical  College  Hospital  ;  Chemist,  State  Board 
of  Health  ;  Professor  of  Chemistry,  Woman's  Medical  College  of  Pennsylvania,  etc. 
i2mo.     660  pages.  Cloth,  $3.00;  Leather,  $3.50 

"To  the  student  of  medical  jurisprudence   and   toxicology  it  is  invaluable,  as  it  is  concise, 
clear,  and  thorough  in  every  respect." — The  American  Journal  of  the  Medical  Sciences. 

Reeves.      Medical  Microscopy. 

Including  Chapters  on  Bacteriology,  Neoplasms,  Urinary  Examination,  etc.  By 
James  E.  Reeves,  m.d.,  ex-President  American  Public  Health  Association,  etc. 
Numerous  Illustrations,  some  of  which  are  printed  in  Colors.      i2mo.       Cloth,  $2.50 

Regis.      Mental  Medicine. 

A  Practical  Manual.  By  Dr.  E.  Regis,  formerly  Chief  of  Clinique  of  Mental  Dis- 
eases, Faculty  of  Medicine  of  Paris.  Authorized  Translation  by  H.  M.  Bannister, 
m.d.,  late  Senior  Assistant  Physician,  Illinois  Eastern  Hospital  for  the  Insane,  etc. 
With  an  Introduction  by  the  Author.      i2mo.  Cloth,  #2.00 

Richardson.      Long  Life 
and  How  to  Reach  It.     By  J.  G.  Richardson,  formerly  Professor  oi  Hygiene,  Uni- 
versity of  Pennsylvania.  Cloth,  .40 

Rockwood.     Chemical  Analysis. 

Introduction  to  Chemical  Analysis  for  Students  of  Medicine,  Pharmacy,  and  Dentistry. 
By  ELBERT  W.  Rockwood,  b.s.,  m.d.,  Professor  of  Chemistry,  Toxicology,  and 
Metallurgy  in  the  Colleges  of  Medicine,  Dentistry,  and  Pharmacy,  University  of  Iowa, 
Iowa  City.      Illustrated.  Cloth,  $1.50 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  33 

Richardson's  Mechanical  Dentistry. 

A  Practical  Treatise  on  Mechanical  Dentistry.  By  Joseph  Richardson,  d.d.s. 
Seventh  Edition,  Thoroughly  Revised  and  in  many  parts  Rewritten  by  Geo.  W. 
Warren,  a.m.,  d.d.s.,  Professor  of  Clinical  Dentistry  and  Oral  Surgery  ;  Chief  of 
the  Clinical  Staff,  Pennsylvania  College  of  Dental  Surgery,  Philadelphia.  With  691 
Illustrations.     Octavo.     675  pages.  Cloth,  $5.00 ;  Leather,  $6.00 

Richter's  Inorganic  Chemistry. 

A  Text-Book  for  Students.  By  Prof.  Victor  von  Richter,  University  of  Breslau. 
Fifth  American  from  Tenth  German  Edition  by  Prof.  H.  Klinger,  University  of 
Kbnigsberg.  Authorized  Translation  by  Edgar  F.  Smith,  m.a.,  ph.d.,  Sc.d., 
Professor  of  Chemistry,  University  of  Pennsylvania  ;  Member  of  the  Chemical  Society 
of  Berlin,  etc.    With  many  Illustrations  and  a  Colored  Plate.     i2mo.       Cloth,  $1.7$ 

Organic  Chemistry. 

The  Chemistry  of  the  Carbon  Compounds.  Third  American  Edition,  Translated 
from  Prof.  Anschutz's  Eighth  German  Edition  by  Edgar  F.  Smith,  m.a., 
ph.d.,  Sc.d.,  Professor  of  Chemistry,  University  of  Pennsylvania.  Revised 
and  Enlarged.      Illustrated.      i2mo.     Two  volumes. 

Vol.    I.     Aliphatic  Series.     625  pages.  Cloth,  $3.00 

Vol.  II.     Carbocyclic  and  Heterocyclic  Series.     671  pages.  Cloth,  $3.00 

Roberts.  Gynecological  Pathology. 
Gynecological  Pathology.  By  Charles  PIurbert  Roberts,  m.d.,  f.r.c.s.,  m.r.c.p., 
Physician  Queen  Charlotte's  Lying-in  Hospital  and  to  the  Samaritan  Hospital  for 
Women  ;  Demonstrator  of  Practical  Midwifery  and  Diseases  of  Women,  and  House 
Surgeon  St.  Bartholomew's  Hospital,  London.  Elaborately  Illustrated  with 
127  Full-Page  Plates  containing  151  Figures,  several  being  printed  in  Colors. 
Octavo.  Extra  Cloth,  C'lt  Top,  $6.00 

Robinson.      Latin  Grammar  of  Pharmacy  and  Medicine. 

By  D.  H.  Robinson,  ph.d.,  Professor  of  Latin  Language  and  Literature,  University 
of  Kansas.     Introduction    by    L.    E.    Sayre,    ph.g.,    Professor    of  Pharmacy   and 
Dean  of  the  Department    of  Pharmacy  in  University  of  Kansas.     Third  Edition, 
Revised  with  the  help  of  Prof.   L.  E.  Sayre,  of  University  of  Kansas,  and  Dr. 
Charles  Rice,  of  the  College  of  Pharmacy  of  the  City  of  New  York.     Cloth,  $1.75 
"  This  method  of  preparing  medical  students  and  pharmacists  for  a  practical  use  of  the  lan- 
guage is  in  every  way  to  be  commended.     .     .      .      Pharmacists  should  know  enough  to  read  pre- 
scriptions readily  and  understandingly." — Johns  Hopkins  Hospital  Bulletin. 

Rosenau.     Disinfection  and  Disinfectants. 

A  Practical  Guide  for  Sanitarians,  Health  and  Quarantine  Officers.  By  M.  J.  Rose- 
nau, m.d.,  Director  of  the  Hygienic  Laboratory  and  PassedAssistant  Surgeon,  U.  S . 
Marine  Hospital  Service,  Washington,  D.  C.     Illustrated.  Cloth,  $2.00 

Sayre.     Organic  Materia  Medica  and  Pharmacognosy. 

An  Introduction  to  the  Study  of  the  Vegetable  Kingdom  and  the  Vegetable  and 
Animal  Drugs.  Comprising  the  Botanical  and  Physical  Characteristics,  Source, 
Constituents,  Pharmacopceial  Preparations  ;  Insects  Injurious  to  Drugs,  and  Phar- 
macal  Botany.  By  L.  E.  Sayre,  b.s.,  ph.m.,  Dean  of  the  School  of  Pharmacy  and 
Professor  of  Materia  Medica  and  Pharmacy  in  the  University  of  Kansas  ;  Member 
Committee  of  Revision  of  the  United  States  Pharmacopoeia,  etc.  With  Sections  on 
Histology  and  Microtechnique  by  William  C.  Stevens,  Professor  of  Botany  in  the 
University  of  Kansas.  Second  Edition,  Revised  and  Enlarged.  With  374  Illustra- 
tions, the  majority  of  which  are  from  Original  Drawings.     8vo.  Cloth,  %\.  50 

Schamberg.     Compend  of  Diseases  of  the  Skin. 

By  Jay  F.  Schamberg,  Professor  of  Diseases  of  the  Skin,  Philadelphia  Polyclinic  ; 
Fellow  of  the  College  of  Physicians  of  Philadelphia  ;  Quiz-Master  at  University  of 
Pennsylvania.  Third  Edition,  Revised  and  Enlarged.  106  Illustrations.  /  Quiz- 
Compend?  Series,  No.  16.  Cloth,  .80;    Interleaved,  $1.00 


34  P.   B LA KIS TON'S  SOAT  <S-    CO.' S 


Scheube.      Diseases  of  Warm  Countries. 

A  Handbook  for  Medical  Men  by  Dr.  B.  Scheube,  State  Physician  and  Sanitary 
Adviser,  Greiz  ;  late  Professor  at  the  Medical  School  in  Kioto,  Japan.  Translated 
from  the  German  by  Pauline  Falcke  and  edited  by  James  Cantlie,  m.a.,  m.b., 
f.r.c.s.,  Lecturer  at  the  London  School  of  Tropical  Medicine  ;  Surgeon  to  the  Sea- 
men's Hospital  Society  Albert  Dock  Hospital,  London  ;  Consulting  Surgeon  Alice 
Memorial  Hospital,  Hong  Kong,  etc.,  with  Addenda  on  Yellow  Fever  by  the  Editor 
and  on  Malaria  by  C.  W.  Daniels,  m.r.c.s.  With  19  Plates  (containing  many 
figures,  29  of  which  are  in  colors)  and  38  other  Illustrations  together  with  5  Colored 
Maps.     Second  Revised  Edition.     Large  Octavo.     Just  Ready.  Cloth,  $8.00 

Schofield.     The  Force  of  Mind, 

or  The  Mental  Factor  in  Medicine.     By  A.  T.  Schofield,  m.d.  Cloth,  $2.00 

Schreiner.     Diet  List. 

Arranged  in  the  Form  of  a  Chart  on  which  Articles  of  Diet  can  be  Indicated  for  any 
Disease.     By  E.  R.  Schreiner,  m.d.     Put  up  in  Pads  of  50  with  Pamphlet  of  Speci- 
men Dietaries.  Per  Pad,  .75 
Scott.     The  Urine :   Its  Chemical  and  Microscopical  Examination. 

By  Lindley  Marcroft  Scott,  m.a.,  m.d.,  etc.  With  41  Colored  Plates  and  other 
Illustrations.     Quarto.  Cloth,  #5.00 

Scoville.     The  Art  of  Compounding.     Second  Edition. 

A  Text-Book  for  Students  and  a  Reference  Book  for  Pharmacists.  By  Wilbur  L. 
Scoville,  ph.g.,  Professor  of  Applied  Pharmacy  and  Director  of  the  Pharmaceutical 
Laboratory  in  the  Massachusetts  College  of  Pharmacy.  Second  Edition,  Enlarged 
and  Improved.  Cloth,  $2.50;  Sheep,  $3.50 

Self-Examination  for  Medical  Students. 

3500  Questions  on  Medical  Subjects,  with  the  proper  References  to  Standard  Books 
in  which  replies  may  be  found,  and  including  Complete  Sets  of  Questions  from  two 
recent  State  Board  Examinations  of  Penn.,  111.,  and  N.  Y.     641110.     Paper,  10  cents. 

Smith.     Abdominal  Surgery.     Sixth  Edition. 

Being  a  Systematic  Description  of  all  the  Principal  Operations.  By  J.  Greig  Smith, 
m.a.,  f.r.s.e.,  Surgeon  to  British  Royal  Infirmary.  224  Illustrations.  Sixth  Edition, 
Enlarged  and  Thoroughly  Revised  by  James  Swain,  m.d.  (Lond.),  f.r.c.s.,  Pro- 
fessor of  Surgery,  University  College,  Bristol,  etc.     Two  vols.     8vo.      Cloth,  $10.00 

Smith.      Bacteriology. 

Lessons  and  Laboratory  Exercises  in  Bacteriology.  An  Outline  of  Technical  Methods 
Introductory  to  the  Systematic  Study  and  Identification  of  Bacteria.  By  Allen  I. 
Smith,  m.d.,  Professor  of  Pathology  in  the  University  of  Texas.  68  Illustrations. 
Interleaved.     Octavo.  Cloth,  #1.50 

Smith.     Electro-Chemical  Analysis. 

By  Edgar  F.  Smith,  m.a.,  ph.d.,  Sc.d.,  Professor  of  Chemistry,  University  of 
Pennsylvania.     Third    Edition,    Revised   and    Enlarged.      39    Illustrations.      i2mo. 

Cloth,  $1.50 
*#*  This  book  has  been  translated  and  published  in  both  Germany  and  France. 

Smith  and  Keller.      Experiments. 

Arranged  for  Students  in  General  Chemistry.  By  Edgar  F.  Smith,  m.a.,  ph.d., 
Sc.d.,  Professor  of  Chemistry,  University  of  Pennsylvania,  and  Dr.  H.  F.  Keller, 
Professor  of  Chemistry,  Philadelphia  High  School.  Fourth  Revised  Edition.  8vo. 
Illustrated.  Cloth,  .60 

Smith.      Dental  Metallurgy. 

A  Manual.  By  Ernest  A.  Smith,  f.c.s.,  Assistant  Instructor  in  Metallurgy,  Royal 
College  of  Science,  London.      Illustrated.     Second  Edition.  Cloth,  #2.00 

Smith.     Wasting  Diseases  of  Infants  and  Children. 

By  Eustace  Smith,  m.d.,  f.r.c.p.,  Physician  to  the  East  London  Hospital  for 
Children,  etc.     Sixth  Edition,  Revised.  Cloth,  $2.00 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  35 

Starling.     Elements  of  Human  Physiology. 

By  Ernest  H.  Starling,  m.d.  (Lond.),  m.r.c.p.,  Joint  Lecturer  on  Physiology  at 
Guy's  Hospital,  London,  etc.     With  ioo  Illus.      i2mo.     437  pages.        Cloth,  $1.00 

Starr.     The  Digestive  Organs  in  Childhood. 

The  Diseases  of  the  Digestive  Organs  in  Infancy  and  Childhood,  with  Chapters  on  the 
Investigation  of  Disease,  The  Management  of  Children,  Massage,  etc.  By  Louis 
Starr,  m.d.,  late  Clinical  Professor  of  Diseases  of  Children  in  the  Hospital  of  the 
University  of  Pennsylvania;  Physician  to  the  Children's  Hospital,  Philadelphia. 
Third  Edition,  Revised  and  Enlarged.     Illustrated.     Octavo.  Cloth,  $3.00 

The  Hygiene  of  the  Nursery. 

Including  the  General  Regimen  and  Feeding  of  Infants  and  Children,  and  the 
Domestic  Management  of  the  Ordinary  Emergencies  of  Early  Life,  Massage,  etc. 
Sixth  Edition,  Enlarged.     25  Illustrations.      i2mo.  Cloth,  $1.00 

*#*  General  and  specific  rules  for  feeding  are  given,  and  Diet  Lists  from  the  first 
week  up  to  the  eighteenth  month,  with  various  recipes  for  artificial  foods,  peptonized 
milk,  etc.  Directions  for  the  sterilization  of  milk,  substitutes  for  milk,  preparation  of 
food  for  both  well  and  sick  children,  nutritious  enemata,  etc. ,  and  the  general  manage- 
ment of  the  Nursery. 

Stearns.     Lectures  on  Mental  Diseases. 

By  Henry  Putnam  Stearns,  m.d.,  Physician-Superintendent  at  the  Hartford  Retreat ; 
Lecturer  on  Mental  Diseases  in  Yale  University.  With  a  Digest  of  Laws  of  the 
Various  States  Relating  to  Care  of  Insane.     Illustrated.     Cloth,  $2.75;  Sheep,  $3.25 

Steell.     The  Physical  Signs  of  Pulmonary  Disease. 

By  Graham  Steel,  m.d.,  f.r.c.p.,  Lecturer  on  Clinical  Medicine  and  on  Diseases  of 
the  Heart  at  Owens  College,  Manchester.     Illustrated.  Cloth,  $1.25 

Stevenson  and  Murphy.     A  Treatise  on  Hygiene. 

By  Various  Authors.     Edited  by  Thomas  Stevenson,   m.d.,  f.r.c.p.,   Lecturer  on 

Chemistry  and  Medical  Jurisprudence  at  Guy's  Hospital,  London,  and  Shirley  F. 

Murphy,   Medical  Officer  of   Health  to  the  County  of   London.     In  three  octavo 

volumes. 

Vol.     I.     With  Plates  and  Wood  Engravings.     Octavo.  Cloth,  $6.00 

Vol.    II.     With  Plates  and  Wood  Engravings.     Octavo.  Cloth,  $6.00 

Vol.  III.     Sanitary  Law.     Octavo.  Cloth,  $5.00 

***  Special  Circular  upon  application. 

Stewart's  Compend  of  Pharmacy. 

Based  upon  "Remington's  Text-Book  of  Pharmacy."  By  F.  E.  Stewart,  m.d., 
ph.g.,  late  Quiz-Master  in  Chemistry  and  Theoretical  Pharmacy,  Philadelphia  College 
of  Pharmacy  ;  Lecturer  on  Pharmacology,  Jefferson  Medical  College.  Fifth  Edition. 
Complete  Tables  of  Metric  and  English  Weights  and  Measures.  ?  Quiz- Compend  t 
Series.  Cloth,  .80  ;  Interleaved  for  the  Addition  of  Notes,  $1.00 

Stirling.     Outlines  of  Practical  Physiology. 

Including  Chemical  and  Experimental  Physiology,  with  Special  Reference  to  Practical 
Medicine.  By  W.  Stirling,  m.d.,  Scd.,  Professor  of  Physiology  and  Histology, 
Owens  College,  Victoria  University,  Manchester  ;  Examiner  in  Physiology,  Univer- 
sities of  Edinburgh  and  London.     Third  Edition.      289  Illustrations.        Cloth,  $2.00 

Outlines  of  Practical  Histology. 

368  Illustrations.  Second  Edition,  Revised  and  Enlarged.  With  new  Illustra- 
tions.     i2mo.  Cloth,  $2.00 


36  P.  BLAKISTON'S  SON  &*   CO.' S 

Stohr.       Text-Book    of    Histology,    Including    the    Microscopical 
Technic.     379  Illustrations.     New  Edition. 

By  Dr.  Philip  Stohr,  Professor  of  Anatomy  at  University  of  Wiirzburg.  Author- 
ized Translation  by  Emma  L.  Bilstein,  m.d.,  formerly  Demonstrator  of  Histology, 
Woman's  Medical  College  of  Penna.  Edited,  with  Additions,  by  Dr.  Alfred 
Schaper,  Professor  of  Anatomy,  University  of  Breslau;  formerly  Demonstrator  of 
Histology,  Harvard  Medical  School,  Boston.  Fourth  American  based  upon  the  Ninth 
German  Edition,  Enlarged  and  Revised.      379  Illustrations.     Octavo.         Cloth,  $3.00 

"  This  edition  of  an  already  well-known  student's  manual  requires  little  but  favorable  com- 
ment. Its  other  editions  have  made  it  well  and  favorably  known,  and  this  one  only  makes  the 
work's  position  more  secure.  The  book  is  not  only  a  useful  one  for  the  student,  but  makes  a  very 
good  work  of  reference  for  its  subject,  and  is  thus  entitled  to  a  place  upon  the  shelves  of  the  prac- 
titioner. ' ' —  The  Medical  Record,  ATew  York. 

Sturgis.     Manual  of  Venereal  Diseases.     Seventh  Edition. 

By  F.  R.  Sturgis,  m.d.,  Sometime  Clinical  Professor  of  Venereal  Diseases  in  the 
Medical  Department  of  the  University  of  the  City  of  New  York  ;  formerly  one  of 
the  Visiting  Surgeons  to  Charity  Hospital,  Blackwells  Island,  Department  of  Vene- 
real Diseases  ;  Member  of  the  American  Association  of  Genito-Urinary  Surgeons,  etc. 
Seventh  Edition,  Revised  and  in  part  Rewritten  by  F.  R.  Sturgis,  m.d.,  and  Follen 
Cabot,  m.d.,  Instructor  in  Genito-Urinary  and  Venereal  Diseases  in  the  Cornell  Uni- 
versity Medical  College  ;  Genito-Urinary  Out-Patient  Surgeon  to  Bellevue  Hospital ; 
Visiting  Dermatologist  to  the  New  York  City  (Charity)  Hospital ;  Lecturer  on  Genito- 
Urinary  and  Venereal  Diseases,  University  of  Vermont,  1900.      i2mo.      200  pages. 

Cloth,  $1.25 

Sutton's  Volumetric  Analysis. 

A  Systematic  Handbook  for  the  Quantitative  Estimation  of  Chemical  Substances  by 
Measure,  Applied  to  Liquids,  Solids,  and  Gases.  Adapted  to  the  Requirements  of 
Pure  Chemical  Research,  Pathological  Chemistry,  Pharmacy,  Metallurgy,  Photog- 
raphy, etc.,  and  for  the  Valuation  of  Substances  Used  in  Commerce,  Agriculture, 
and  the  Arts.  By  Francis  Sutton,  f.cs.  Eighth  Edition,  Revised  and  Enlarged. 
With  116  Illustrations.      8vo.  Cloth,  $5.00 

Swanzy.     Diseases  of  the  Eye  and  their  Treatment. 

A  Handbook  for  Physicians  and  Students.  By  Henry  R.  Swanzy,  a.m.,  m.b., 
f.r.c.s.l,  Examiner  in  Ophthalmology,  University  of  Dublin  ;  Surgeon  to  the  National 
Eye  and  Ear  Infirmary  ;  Ophthalmic  Surgeon  to  the  Adelaide  Hospital,  Dublin. 
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"  Is  without  doubt  the  most  satisfactory  manual  we  have  upon  diseases  of  the  eye.  It  occu- 
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encyclopedic  treatises,  which  are  too  extended  and  detailed  to  be  of  special  use  to  the  general 
practitioner." — Chicago  Medical  Recorder. 

Symonds.      Manual  of  Chemistry 

for  Medical  Students.  By  Brandreth  Symonds,  a.m.,  m.d.,  Assistant  Physician 
Roosevelt  Hospital,  Out-Patient  Department,  New  York.     Second  Edition,      nmo. 

Cloth,  $2.00 

Taft.      Index  of  Dental  Periodical  Literature. 

By  Jonathan  Taft,  d.d.s.     8vo.  Cloth,  #2.00 

Tanner's  Memoranda  of  Poisons 

and  their  Antidotes  and  Tests.  By  THOS.  Hawkes  Tanner,  m.d.  Ninth  Edition, 
Revised  by  Henry  Lefemann,  m.d.,  Professor  of  Chemistry,  Woman's  Medical  Col- 
lege of  Penna.;  Vice-President  Society  of  Public  Analysts.      i2mo.  Cloth,  .75 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  37 

Tavera.     Medicinal  Plants  of  the  Philippines. 

By  T.  H.  Pardo  de  Tavera,  Doctor  of  Medicine  in  Faculty  of  Paris  ;  Scientific 
Commissioner  S.M.  in  Philippine  Islands,  etc.  Translated  and  Revised  by  Jerome 
B.  Thomas,  Jr.,  a.b.,  m.d.,  Captain  and  Assistant  Surgeon  United  States  Volunteers. 

Cloth,  $2.00 

Taylor.     Practice  of  Medicine. 

By  Frederick  Taylor,  m.d.,  Physician  to,  and  Lecturer  on  Medicine  at,  Guy's 
Hospital,  London  ;  Physician  to  Evelina  Hospital  for  Sick  Children.  Sixth  Edition, 
Revised.  Cloth,  $4.00 

Taylor  and  Wells.  Diseases  of  Children.  Illustrated. 
A  Manual  for  Students  and  Physicians.  By  John  Madison  Taylor,  a.m.,  m.d., 
Professor  of  Diseases  of  Children,  Philadelphia  Polyclinic  ;  Pediatrist  to  the  Philadel- 
phia Hospital  ;  Assistant  Physician  to  the  Children's  Hospital ;  Consulting  Physician 
to  the  Elwyn  and  the  Vineland  Training  Schools  for  Feeble-minded  Children ; 
Neurologist  to  the  Howard  Hospital,  etc.;  and  William  H.  Wells,  m.d.,  Adjunct 
Professor  of  Obstetrics  and  Diseases  of  Infancy  in  the  Philadelphia  Polyclinic  ; 
Demonstrator  of  Clinical  Obstetrics,  Jefferson  Medical  College  ;  Chief  Gynecologist, 
Mt.  Sinai  Hospital.  With  Numerous  Illustrations.  Second  Edition,  Revised  and 
Enlarged.     Octavo.  Cloth,  $4.50 

Temperature  Charts 

for  Recording  Temperature,  Respiration,  Pulse,  Day  of  Disease,  Date,  Age,  Sex, 
Occupation,  Name,  etc.  Put  up  in  pads  ;  each  .50 

Thayer.     Compend  of  General  Pathology. 

Specially  adapted  for  Medical  Students  and  Physicians.  By  A.  E.  Thayer,  m.d., 
Assistant  Instructor  in  Pathology,  Cornell  Medical  School ;  Pathologist  to  the  City 
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Compend  of  Special  Pathology.     34  Illustrations. 

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Thorington.     Retinoscopy.     Fourth  Edition. 

(The  Shadow  Test)  in  the  Determination  of  Refraction  at  One  Meter  Distance  with 
the  Plane  Mirror.  By  James  Thorington,  a.m.,  m.d.,  Professor  of  Diseases  of  the 
Eye  in  the  Philadelphia  Polyclinic  ;  Ophthalmologist  to  the  Elwyn,  Vineland,  and 
New  Jersey  State  Training  Schools  for  Feeble-minded  Children  ;  Lecturer  on  the 
Anatomy,  Physiology,  and  Care  of  the  Eyes  in  the  Philadelphia  Manual  Training 
Schools,  etc.  51  Illustrations,  several  of  which  are  Colored.  Fourth  Edition,  En- 
larged.     i2mo.  Cloth,  $1.00 

Refraction  and  How  to  Refract.     Second  Edition. 

With  200  Illustrations,  most  of  which  are  made  from  Original  Drawings,  and 
13  of  which  are  in  Colors.     Second  Edition,  Revised.     i2mo.  Cloth,  $1.50 

Synopsis  of  Contents. — I.  Optics.  II.  The  Eye  ;  The  Standard  Eye ; 
Cardinal  Points  ;  Visual  Angle  ;  Minimum  Visual  Angle  ;  Standard  Acuteness  of 
Vision  ;  Size  of  Retinal  Image,  Accommodation  ;  Mechanism  of  Accommoda- 
tion ;  Far  and  Near  Point  ;  Determination  of  Distant  Vision  and  Near  Point ; 
Amplitude  of  Accommodation  ;  Convergence  ;  Angle  Gamma  ;  Angle  Alpha. 
III.  Ophthalmoscope  ;  Direct  and  Indirect  Method.  IV.  Emmetropia  ;  Hyper- 
opia ;  Myopia.  V.  Astigmatism  or  Curvature  Ametropia  ;  Tests  for  Astigma- 
tism. VI.  Retinoscopy.  VII.  Muscles.  VIII.  Cycloplegics  ;  Cycloplegia  ; 
Asthenopia ;  Examination  of  the  Eyes.  IX.  How  to  Refract.  X.  Applied 
Refraction.  XI.  Presbyopia ;  Aphakia ;  Anisometropia ;  Spectacles.  XII. 
Lenses  ;  Spectacle  and  Eye  Glass  Frames  ;  How  to  Take  Measurements  for 
Them  and  How  They  Should  be  Fitted.      Index. 


38  P.  BLAKISTON'S  SON  <S-    CO.' S 

Thorne.     The   Schott   Methods  of  the  Treatment  of  Chronic  Dis- 
eases of  the  Heart. 

With  an  Account  of  the  Nauheim  Baths  and  of  the  Therapeutic  Exercises.  By  W. 
Bezly  Thorne,  m.d.,  m.r.c.p.  With  Plates  and  Numerous  other  Illustrations. 
Fourth  Edition,  Revised  and  Enlarged.     Octavo.  Cloth,  $2.00 

Thresh.     Water  and  Water  Supplies. 

By  John  C.  Thresh,  d.sc.  (Lond.),  m.d.,  d.p.h.  (Cambridge),  Medical  Officer  of 
Health  to  the  Essex  County  Council;  Lecturer  on  Public  Health,  King's  College, 
London  ;  Fellow  of  the  Institute  of  Chemistry  ;  Member  Society  Public  Analysts, 
etc.  Third  Edition,  Revised  and  very  much  Enlarged.  Illustrated.  527  pages. 
i2mo.  Cloth,  $2.00 

Tissier.     Pneumatotherapy  and  Inhalation  Methods. 

See  Cohen,  Physiologic  Therapeutics,  page  10. 

Tomes'  Dental  Anatomy. 

A  Manual  of  Dental  Anatomy,  Human  and  Comparative.  By  C.  S.  Tomes,  d.d.s. 
263  Illustrations.     Fifth  Edition.  i2mo.  Cloth,  $4.00 

Dental  Surgery. 

A  System  of  Dental  Surgery.  By  John  Tomes,  f.r.s.  Fourth  Edition,  Thor- 
oughly Revised  by  C.  S.  Tomes,  d.d.s.  With  289  Illustrations.  i2mo.  717 
pages.  Cloth,  $4.00 

Traube.     Physico-Chemical  Methods. 

By  Dr.  J.  Traube,  Privatdocent  in  the  Technical  High  School  of  Berlin.  Author- 
ized Translation  by  W.  D.  Hardin,  Harrison  Senior  Fellow  in  Chemistry,  University 
of  Pennsylvania.     With  97  Illustrations.     8vo.  Cloth,  $1.50 

Treves.     German-English  Medical  Dictionary. 
By   Frederick   Treves,    f.r.cs.,    assisted  by  Dr.   Hugo  Lang,  b.a.  (Munich). 
i2mo.  Half  Calf,  $3.25 

Physical  Education  :   Its  Effects,  Value,  Methods,  etc.      8vo. 

Cloth,  .75 
Tuke.      Dictionary  of  Psychological  Medicine. 

Giving  the  Definition,  Etymology,  and  Synonyms  of  the  Terms  used  in  Medical  Psy- 
chology, with  the  Symptoms,  Pathology,  and  Treatment  of  the  Recognized  Forms  of 
Mental  Disorders,  together  with  the  Law  of  Lunacy  in  Great  Britain  and  Ireland. 
Edited  by  D.  Hack  Tuke,  m.d.,  ll.d.,  Examiner  in  Mental  Physiology  in  the  Uni- 
versity of  London.  Two  volumes.  Octavo.  Cloth,  #10.00 
"  A  comprehensive,  standard  book." — The  British  Medical  Journal. 

"  It  is  vastly  more  than  a  Dictionary.  It  is  an  elaborate  and  complete  Encyclopaedia  of 
Psychological  Medicine ;  in  fact,  a  small  library  in  itself  on  that  subject.  The  high  expectations 
which  Dr.  Tuke's  work  in  this  field  had  raised  are  more  than  fulfilled.  ...  It  will  be  found 
to  be  a  most  useful  reference  handbook  for  the  alienist  and  student.  The  general  physician  also 
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Journal. 

"We  believe  that  the  student  might  obtain  a  better  knowledge  of  insanity  from  this  work  than 
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else  accessible." — American  Journal  of  Insanity. 

Turnbull's  Artificial  Anesthesia. 

A  Manual  of  Anesthetic  Agents  in  the  Treatment  of  Diseases,  also  their  Employment 
in  Dental  Surgery  ;  Modes  of  Administration  ;  Considering  their  Relative  Risks  ; 
Tests  of  Purity  ;  Treatment  of  Asphyxia  ;  Spasms  of  the  Glottis  ;  Syncope,  etc.  By 
Laurence  Turnhull,  m.d.,  PH.G.,  Aural  Surgeon  to  Jefferson  College  Hospital,  etc. 
Fourth  Edition,  Revised.      54  Illustrations.      121110.  Cloth,  #2.50 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  39 

Tyson.     The  Practice  of  Medicine.     Second  Edition. 

A  Text-Book  for  Physicians  and  Students,  with  Special  Reference  to  Diagnosis  and 
Treatment.  By  James  Tyson,  m.d.,  Professor  of  Medicine  in  the  University  of 
Pennsylvania;  Physician  to  the  University  and  to  the  Philadelphia  Hospitals,  etc. 
With  Colored  Plates  and  many  other  Illustrations.  Second  Edition,  Revised  and 
Enlarged.      127  Illustrations.     8vo.      1222  pages. 

Cloth,  $5.50;  Leather,  $6.50;  Half  Russia,  #7.50 

*#*  This  edition  has  been  entirely  reset  from  new  type.  The  author  has  revised  it 
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"  This  work  not  only  represents  the  work  of  a  practitioner  of  great  experience,  but  of  a  care- 
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separating  the  true  from  the  false." — The  Journal  of  the  American  Medical  Association,  Chicago. 

"  Represents  the  outcome  of  much  well-directed  labor,  and  constitutes  a  reliable  and  useful 
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years.  Moreover,  he  entered  medicine  through  the  portal  of  pathology,  a  decided  advantage  in 
the  writer  of  a  text-book.  .  .  .  The  typography  is  decidedly  above  works  of  this  class  issued 
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*£.*  Sample  Pages  and  Illustrations  sent  free  upon  application. 

Guide  to  the  Examination  of  Urine.     Tenth  Edition. 

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to  being  a  classic  on  the  subject  of  which  it  treats  as  does  this  one." — Buffalo  Medical '  Jozimal. 

Handbook  of  Physical  Diagnosis. 

Fourth  Edition,  Revised  and  Enlarged.  With  two  Colored  Plates  and  55  other 
Illustrations.     298  pages.      i2mo.  Cloth,  $1.50 

Cell  Doctrine. 

Its  History  and  Present  State.     Second  Edition.  Cloth,  $1.50 

United  States  Pharmacopoeia,  1890. 

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Select  Tables  from  the  U.  S.  P. 

Being  Nine  of  the  Most  Important  and  Useful  Tables,  printed  on  Separate 
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40  P.  BLAKISTON'S  SOX  &«   CO.'S 

Ulzer  and  Fraenkel.  Introduction  to  Chemical-Technical  Analysis. 
By  Prof.  F.  Ulzer  and  Dr.  A.  Fraenkel,  Directors  of  the  Testing  Laboratory  of 
the  Royal  Technological  Museum,  Vienna.  Authorized  Translation  by  Hermann 
Fleck,  nat.sc.d.,  Instructor  in  Chemistry  and  Chemical  Technical  Analysis  in  the 
John  Harrison  Laboratory  of  Chemistry,  University  of  Pennsylvania,  with  an 
Appendix  by  the  Translator  relating  to  Food  Stuffs,  Asphaltum,  and  Paint.  1 2  Illus- 
trations.    8vo.  Cloth,  $1.25 

Van  Niiys  on  the  Urine. 

Chemical  Analysis  of  Healthy  and  Diseased  Urine,  Qualitative  and  Quantitative.  By 
T.  C.  Van  Nuys.      39  Illustrations.     Octavo.  Cloth,  $1.00 

Van  Harlingen  on  Skin  Diseases. 

A  Practical  Manual  of  Diagnosis  and  Treatment,  with  Special  Reference  to  Differential 
Diagnosis.  By  Arthur  Van  Harlixgen,  m.d.,  Emeritus  Professor  of  Diseases  of 
the  Skin  in  the  Philadelphia  Polyclinic  ;  Dermatologist  to  the  Children's  Hospital. 
Third  Edition,  Revised  and  Enlarged.  With  Formulae  and  Illustrations,  several  being 
in  Colors.      580  pages.  Cloth,  $2.75 

"  As  would  naturally  be  expected  from   the   author,   his  views  are  sound,  his  information 

extensive,  and  in  matters  of  practical  detail  the  hand  of  the  experienced  physician  is  everywhere 

visible." — The  Medical  Ntivs. 

Virchow's  Post-mortem  Examinations. 

A  Description  and  Explanation  of  the  Method  of  Performing  them  in  the  Dead- 
House  of  the  Berlin  Charite  Hospital,  with  Especial  Reference  to  Medico-Legal 
Practice.  By  Professor  Virchow.  Translated  by  Dr.  T.  P.  Smith.  Illustrated. 
Third  Edition.  Cloth,  .75 

Voswinkel.      Surgical  Nursing. 

A  Manual  for  Nurses.  By  Bertha  M.  Voswinkel,  Graduate  Episcopal  Hospital, 
Philadelphia;  late  Nurse-in-Charge  Children's  Hospital,  Columbus,  O.  Second 
Edition,  Revised  and  Enlarged,      in  Illustrations.      i2mo.  Cloth,  $1.00 

Walker.     Students'  Aid  in  Ophthalmology. 

By  Gertrude  A.  Walker,  a.b.,  m.d.,  Clinical  Instructor  in  Diseases  of  the  Eye  at 
Woman's  Medical  College  of  Pennsylvania.  40  Illustrations  and  Colored  Plate. 
i2mo.  Cloth,  $1.50 

Walsham.     Surgery  :    Its  Theory  and  Practice.     Seventh  Edition. 

For  Students  and  Physicians.  By  Wm.  J.  Walsham,  m.d.,  f.r.cs.,  Senior  Assist- 
ant Surgeon  to,  and  Demonstrator  of  Practical  Surgery  in,  St.  Bartholomew's  Hospital  ; 
Surgeon  to  Metropolitan  Free  Hospital,  London.  Seventh  Edition,  Revised  and  En- 
larged by  100  pages.     With  483  Illustrations  and  28  Skiagrams.  Cloth,  $3.50 

Warren.     Compend  of  Dental  Pathology  and  Dental  Medicine. 

Containing  all  the  most  Noteworthy  Points  of  Interest  to  the  Dental  Student  and  a 
Chapter  on  Emergencies.  By  George  W.  Warren,  d.d.s.,  Professor  of  Clinical 
Dentistry  and  Oral  Surgery  ;  Clinical  Chief,  Pennsylvania  College  of  Dental  Surgery, 
Philadelphia.  Third  Edition,  Enlarged.  Illustrated.  Being  No.  13  ? Quiz- Com- 
pend? Series.      i2mo.  Cloth,  .80  ;  Interleaved  for  the  Addition  of  Notes,  $1.00 

Dental  Prosthesis  and  Metallurgy. 

129  Illustrations.  Cloth,  $1.25 

Weber    and     Hinsdale.       Climatology — Health     Resorts — Mineral 
Springs. 

See  Cohen,  Physiologic  Therapeutics,  page  10. 


MEDICAL  AND   SCIENTIFIC  PUBLICATIONS.  41 

Wells.     Compend  of  Gynecology. 

By  Wm.  H.  Wells,  m.d.,  Demonstrator  of  Clinical  Obstetrics,  Jefferson  Medical 
College,  Philadelphia  ;  Chief  Gynecologist  Mt.  Sinai  Hospital  ;  Fellow  of  the  College 
of  Physicians  of  Philadelphia.  Third  Edition,  Revised.  140  Illustrations.  Being 
No.  7  ? Quiz-  Comfte7id '?  Series.      i2mo.         Cloth,  .80;  Interleaved  for  Notes,  $1.00 

Wethered.     Medical  Microscopy. 

A  Guide  to  the  Use  of  the  Microscope  in  Practical  Medicine.  By  Frank  J.  Weth- 
ered, m.d.,  m.r.c.p.,  Demonstrator  of  Practical  Medicine,  Middlesex  Hospital  Med- 
ical School ;  Assistant  Physician,  late  Pathologist,  City  of  London  Hospital  for 
Diseases  of  the  Chest,  etc.  With  a  Colored  Plate  and  101  Illustrations.  406  pages. 
i2mo.  Cloth,  $2.00 

Weyl.     Sanitary  Relations  of  the  Coal-Tar  Colors. 

By  Theodore  Weyl.  Authorized  Translation  by  Henry  Leffmann,  m.d.,  ph.d. 
i2mo.  Cloth,  $1.25 

Whitacre.     Laboratory  Text-Book  of  Pathology. 

By  Horace  J.  Whitacre,  m.d.,  Demonstrator  of  Pathology,  Medical  College  of 
Ohio,  Cincinnati.  Illustrated  with  121  Original  Drawings  and  Microphotographs. 
8vo.  Cloth,  $1.50 

White.     The  Mouth  and  Teeth.     Illustrated. 
By  J.  W.  White,  m.d.,  d.d.s.  Cloth,  .40 

White  and  Wilcox.     Materia  Medica,  Pharmacy,  Pharmacology,  and 

Therapeutics.     Fifth  Edition. 

A  Handbook  for  Students.  By  W.  Hale  White,  m.d.,  f.r.cp.,  etc.,  Physician  to, 
and  Lecturer  on  Materia  Medica  and  Therapeutics,  Guy's  Hospital;  Examiner  in 
Materia  Medica  to  the  Conjoint  Board,  etc.  Fifth  American  Edition,  Revised  by 
Reynold  W.  Wilcox,  m.a.,  m.d.,  ll.d.,  Professor  of  Clinical  Medicine  and  Thera- 
peutics at  the  New  York  Post-Graduate  Medical  School  and  Hospital ;  Visiting  Phy- 
sician, St.  Mark's  Hospital  ;  Assistant  Visiting  Physician,  Bellevue  Hospital.  En- 
larged and  Improved.      i2mo.  Cloth,  $3.00;  Leather,  #3.50 

Williams.     Manual  of  Bacteriology.     Second  Edition. 

By  Herbert  U.  Williams,  m.d.,  Professor  of  Pathology  and  Bacteriology,  Medical 
Department,  University  of  Buffalo.  Second  Edition,  Revised  and  Enlarged.  90 
Illustrations.      i2mo.      290  pages.  Cloth,  $1.50 

Wilson.     Handbook  of  Hygiene  and  Sanitary  Science. 

By  George  Wilson,  m.a.,  m.d.,  f.r.s.e.,  Medical  Officer  of  Health  for  Mid-War- 
wickshire, England.    With  Illustrations.    Eighth  Edition.     i2mo.  Cloth,  #3.00 

Wilson.     The  Summer  and  its  Diseases. 

By  James  C.  Wilson,  m.d.,  Professor  of  the  Practice  of  Medicine  and  Clinical 
Medicine,  Jefferson  Medical  College,  Philadelphia.  Cloth,  .40 

Wilson.      System  of  Human  Anatomy. 

Eleventh  Revised  Edition,  Edited  by  Henry  Edward  Clark,  m.d.,  m.r.cs.  492 
Illustrations,  26  Colored  Plates,  and  a  Glossary  of  Terms.      i2mo.  Cloth,  $5.00 

Winckel.     Text-Book  of  Obstetrics. 

Including  the  Pathology  and  Therapeutics  of  the  Puerperal  State.  By  Dr.  F. 
Winckel,  Professor  of  Gynecology,  Royal  University  Clinic  for  Women  in  Munich. 
Authorized  Translation  by  J.  Clifton  Edgar,  a.m.,  m.d.,  Professor  of  Obstetrics 
and  Clinical  Midwifery,  Cornell  University  Medical  Department,  New  York.  190 
Illustrations.     Octavo.  Cloth,  $5.00  ;  Leather,  $6.00 


42 


P.  BLAKISTON'S  SON  &-   CO/ S  PLBLICATIONS. 


Winternitz.     Hydrotherapy — Thermotherapy — Balneology. 

See  Cohen,  Physiologic  Therapeutics,  page  10. 

Wood.     Brain  Work  and  Overwork. 

By  H.  C.  Wood,  Clinical  Professor  of  Nervous  Diseases,  University  of  Pennsylvania. 
i2mo.  Cloth,  .40 

Woody.     Essentials  of  Medical  and  Clinical  Chemistry. 

With  Laboratory  Exercises.  By  Samuel  E.  Woody,  a.m.,  m.d.,  Professor  of  Chem- 
istry and  Diseases  of  Children  in  the  Medical  Department,  Kentucky  University, 
Louisville.     Fourth  Edition,  Revised  and  Enlarged.     Illustrated.    i2mo.    Cloth,  $1.50 

"  The  fact  that  Prof.  Woody's  little  book  has  reached  a  third  edition  in  such  a  short  time  is 
sufficient  proof  of  its  usefulness  for,  and  demand  by,  the  medical  student.  The  selection  of  the 
material  and  its  plan  of  presentation,  resulting  from  the  author's  large  experience  as  a  practitioner 
and  teacher  of  medical  chemistry,  is  well  intended  to  offer  to  the  student  that  which  is  really  essen- 
tial for  his  limited  college  course,  and,  it  is  to  be  hoped,  a  basis  for  further  instruction  in  the  impor- 
tant branch  of  medical  science." — The  American  Journal  of  Medical  Sciences,  Philadelphia. 

Wright.     Ophthalmology.     New  Edition.      117  Illustrations. 

A  Text-Book  by  John  W.  Wright,  a.m.,  m.d.,  Professor  of  Ophthalmology  and 
Clinical  Ophthalmology  in  Ohio  Medical  University  ;  Ophthalmologist  to  the  Protest- 
ant and  University  Hospitals,  etc.  Second  Edition,  Revised,  Rewritten,  and  Enlarged. 
With  many  new  Illustrations.  Cloth,  $3.00 


THE  STANDARD  TEXT=BOOK 


New  Edition 

Third  Revised  Edition,  Enlarged  and  Improved 

846  Illustrations,  of  which  267  are  Colored 

Octavo.    J328  Pages.    Cloth,  $6.00;  Leather,  $7.00 

"  Morris'  Anatomy"  was  published  at  a  time  when  methods  of  teaching, 
the  art  of  engraving,  and  distinct  advance  in  anatomical  illustration 
made  desirable  a  new  and  modern  text-book.  The  rapid  sale  of  the  first 
edition,  its  immediate  adoption  as  a  text-book  by  a  large  number  of  medi- 
cal schools,  and  its  purchase  by  physicians  and  surgeons  proved  its  value 
and  made  it  from  the  day  of  publication  a  standard  authority. 

In  making  this  new  edition  the  editors  and  publishers  have  used  every 
endeavor  to  enhance  its  value.  The  text  has  been  thoroughly  revised  and 
in  many  parts  rewritten ;  the  editor  has  devoted  himself  to  the  task  of 
making  it  a  harmonious  whole ;  many  new  illustrations  have  replaced 
those  used  in  the  first  edition,  and  a  large  number  have  been  printed  in 
colors,  while  the  typographical  appearance  has  been  improved  in  several 
particulars. 

The  illustrations,  in  correctness  and  excellence  of  execution,  are  equaled 
by  no  similar  treatise;  about  #1000  having  been  expended  on  new  and 
improved  blocks  for  this  edition  alone. 

"  The  evergrowing  popularity  of  the  book  with  teachers  and  students  is  an  index  of  its  value, 
and  it°may  safely  be  recommended  to  all  interested." — Medical  Record,  New  York. 

"  ( )f  all  the  text-books  of  moderate  size  on  human  anatomy  in  the  English  language,  Morris 
is  undoubtedly  the  most  up-to-date  and  accurate." — Pliiladelphia  Medical  Journal. 

V  CIRCULAR  WITH  SAMPLE  PAGES  AND  ILLUSTRATIONS  FREE. 


THUMB 
INDEX 
IN  EACH 
COPY 


From  the  Southern  Clinic. 

"  We  know  of  no  series  of  books  issued  by  any  house  that  so  fully  meets  our  approval  as  these 
?  Quiz-Compends  ?.  They  are  well  arranged,  full,  and  concise,  and  are  really  the  best  line  of  text* 
books  that  could  be  found  for  either  student  or  practitioner." 


BLAKISTON'S  ?QUIZ=COMPENDS? 

The  Best  Series  of  Manuals  for  the  Use  of  Students. 

Price  of  each,  Cloth,  .80.       Interleaved  for  taking  Notes,  81.00. 

gg^These  Compends  are  based  on  the  most  popular  text-books  and  the  lectures  of  prominent 
professors,  and  are  kept  constantly  revised,  so  that  they  may  thoroughly  represent  the  present  state 
of  the  subject  upon  which  they  treat.  The  authors  have  had  large  experience  as  Quiz-Masters 
and  attaches  of  colleges,  and  are  well  acquainted  with  the  wants  of  students.  They  are  arranged 
in  the  most  approved  form,  thorough  arid  concise,  containing  over  900  illustrations,  inserted 
wherever  they  could  be  used  to  advantage.  Can  be  used  by  students  of  any  college,  and  contain 
information  nowhere  else  collected  in  such  a  condensed  practical  shape. 

No.  1.  HUMAN  ANATOMY.  Sixth  Revised  and  Enlarged  Edition.  Including  Vis- 
ceral Anatomy.  Can  be  used  with  either  Morris's  or  Gray's  Anatomy.  117  Illustrations  and 
16  Lithographic  Plates  of  Nerves  and  Arteries,  with  Explanatory  Tables,  etc.  By  Samuel 
O.  L.  Potter,  m.d.,  formerly  Professor  of  the  Practice  of  Medicine,  Cooper  Medical  College, 
San  Francisco;   Major  and  Brigade  Surgeon,  U.  S.  Vol. 

No.  2.  PRACTICE  OF  MEDICINE.  Part  I.  Sixth  Edition,  Revised,  Enlarged,  and 
Improved.  By  Dan'l  E.  Hughes,  m.d.,  Physician-in-Chief,  Philadelphia  Hospital;  late 
Demonstrator  of  Clinical  Medicine,  Jefferson  Medical  College,  Philadelphia. 

No.  3.  PRACTICE  OF  MEDICINE.  Part  II.  Sixth  Edition,  Revised,  Enlarged,  and 
Improved.     Same  author  as  No.  2. 

No.  4.  PHYSIOLOGY.  Eleventh  Edition,  with  new  Illustrations.  Enlarged  and  Revised. 
By  A.  P.  Brubaker,  m.d.,  Professor  of  Physiology  in  the  Pennsylvania  College  of  Dental 
Surgery;  Adjunct  Professor  of  Physiology,  Jefferson  Medical  College,  Philadelphia. 

No.  5.  OBSTETRICS.  Seventh  Edition.  By  Henry  G.  Landis,  m.d.  Revised  and 
Edited  by  Wm.  H.  Wells,  m.d.,  Demonstrator  of  Clinical  Obstetrics,  Jefferson  Medical 
College,  Philadelphia.     Enlarged.     52  Illustrations. 

No.  6.  MATERIA  MEDIC  A,  THERAPEUTICS,  AND  PRESCRIPTION 
WRITING.     Sixth  Revised  Edition.     Same  author  as  No.  1. 

No.  7.  GYNECOLOGY.  Third  Edition.  By  Wm.  H.  Wells,  m.d.,  Demonstrator  of 
Clinical  Obstetrics,  Jefferson  Medical  College,  Philadelphia.      140  Illustrations. 

No.  8.  DISEASES  OF  THE  EYE  AND  REFRACTION.  Second  Edition.  Includ- 
ing Treatment  and  Surgery  and  a  Section  on  Local  Therapeutics.  By  George  M.  Gould, 
M.D.,  Editor  Philadelphia  Medical  Journal,  and  W.  L.  Pyle,  M.d.  ,  Assistant  Surgeon,  Wills 
Eye  Hospital.     With  Formulae,  Glossary,  several  useful  Tables,  and  109  Illustrations. 

No.  9.  SURGERY,  Minor  Surgery,  and  Bandaging.  Fifth  Edition,  Enlarged  and  Im- 
proved. By  Orville  Horwitz,  B.S.,  m.d.,  Clinical  Professor  of  Gen ito- Urinary  Surgery 
and  Venereal  Diseases  in  Jefferson  Medical  College ;  Surgeon  to  Philadelphia  Hospital,  etc. 
With  98  Formulae  and  167  Illustrations. 

No.  10.  MEDICAL  CHEMISTRY.  Fourth  Edition.  Including  Urinalysis,  Chemistry  of 
Milk,  Blood,  etc.  By  Henry  Leffmann,  m.d.,  Professor  of  Chemistry  in  Pennsylvania 
College  of  Dental  Surgery  and  in  the  Woman's  Medical  College,  Philadelphia. 

No.  n.  PHARMACY.  Fifth  Edition.  Based  upon  Professor  Remington's  Text-Book  of 
Pharmacy.  By  F.  E.  Stewart,  m.d.,  ph.g.,  late  Quiz-Master  in  Pharmacy  and  Chemistry, 
Philadelphia  College  of  Pharmacy ;  Lecturer  at  Jefferson  Medical  College. 

No.  12.  VETERINARY  ANATOMY  AND  PHYSIOLOGY.  Illustrated.  By  Wm. 
R.  Ballou,  m.d.,  Professor  of  Equine  Anatomy  at  New  York  College  of  Veterinary  Sur- 
geons ;   Physician  to  Bellevue  Dispensary,  etc.     With  29  graphic  Illustrations. 

No.  13.  DENTAL  PATHOLOGY  AND  DENTAL  MEDICINE.  Third  Edition, 
Illustrated.     By  George  W.  Warren,  d.d.s.,  Pennsylvania  College  of  Dental  Surgery. 

No.  14.  DISEASES  OF  CHILDREN.  Colored  Plate.  By  Marcus  P.  Hatfield, 
Professor  of  Diseases  of  Children,  Chicago  Medical  College.      Third  Edition.     Just  Ready. 

No.  15.     GENERAL  PATHOLOGY.  Illustrated.  By  A.  E.  Thayer,  m.d.,  etc. 

No.  16.  DISEASES  OF  THE  SKIN.  By  Jay  F.  Schamberg,  m.d.,  Professor  of  Skin 
Diseases,  Philadelphia  Polyclinic.      Third  Edition,  Revised.      Ic6  Illustrations. 

No.  17.     HISTOLOGY.     Illustrated.     By  H.  H.  Cushing,  m.d.  Preparing. 

No.  18.     SPECIAL  PATHOLOGY.     Illustrated.     By  same  author  as  No.  15.     Jusl  Ready. 

No.  19.     KYLE— EAR,  NOSE,   AND  THROAT.     Illustrated.  In  Press. 

43 


PRACTICAL  GYNECOLOGY 

A  Modern  Comprehensive  Text-Book 
By  E.  E.  MONTGOMERY,  MX). 

Professor  of  Gynecology,  Jefferson  Medical  College?   Gynecologist  to  the  Jefferson  Medical 

College  and  St.  Joseph's  Hospitals ;   Consulting  Gynecologist  to 

the  Philadelphia  Lying-in  Charity 

WITH  FIVE  HUNDRED  AND  TWENTY-SEVEN 
ILLUSTRATIONS 

Nearly  all  of  which  have  been  Drawn  and  Engraved  Specially  for  this 
Work,  for  the  most  part  from  Original  Sources 

OCTAVO.    819  PAGES.    CLOTH,  $5.00  j  LEATHER,  $6.00 


From  THE  JOURNAL  OF  THE  AMERICAN  MEDICAL  ASSOCIATION. 

"  Fashion  in  medical  book-making  seems  to  be  running  to  the  composite,  which 
may  be  advantageous  and  the  means  of  producing  a  better  book  than  one  written  by 
an  individual.  It  may  be  the  old-fashioned  notions  of  the  reviewer,  but  he  belives  in 
the  old  idea  of  one  book,  one  author,  and  he  should  have  all  the  responsibility,  all  the 
criticism,  and  all  the  glory  that  attach  to  it.  The  composite  is  likely  to  be  written 
under  a  '  rush  '  order — so  much  space,  in  so  much  time,  for  so  much  money.  The  work 
before  us  is  the  work  of  one  individual,  and  the  personality  of  that  individual  is  evident 
through  the  whole  book.  .  .  .  The  result  shows  painstaking  effort  in  every  detail, 
in  conciseness  of  statements,  in  arrangement  of  subjects,  and  in  the  systematic  order 
and  completeness  in  which  each  is  considered.  .  .  .  The  author  is  neither  too 
radical  nor  too  conservative  in  his  consideration  of  the  conditions  that  may  need  radical 
operations.  In  the  introduction  he  tells  us  that  the  true  gynecologist  must  be  '  so  con 
servative  that  he  will  sacrifice  no  organ  whose  physiologic  integrity  is  capable  of  being 
restored;  so  bold  and  courageous  that  his  patient  shall  not  forfeit  her  opportunity  for 
life  or  restored  health  through  his  failure  to  assume  the  responsibility  of  any  operative 
procedure  necessary  to  secure  the  object.'  This  is  the  basal  idea  that  permeates  the 
book  :  the  ultra-radical  operator  will  find  no  endorsement,  and  the  'tinkering'  gynecologist- 
he  who  treats  all  diseases  of  women  by  means  of  a  pledget  of  cotton  and  a  speculum — 
no  encouragement  in  its  pages. 

"The  book  is  one  that  can  be  recommended  to  the  student,  to  the  general  practi- 
tioner— who  must  sometimes  be  a  gynecologist  to  a  certain  extent  whether  he  will  or  not 
— and  to  the  specialist,  as  an  ideal  and  in  every  way  complete  work  on  the  gynecology  of 
to-day — a  practical  work  for  practical  workers." 


DESCRIPTIVE  CIRCULAR  UPON  APPLICATION. 

44 


NOW     READY 


DISEASES  OF  THE 

SKIN 

Their  Description,    Pathology,    Diagnosis,  and    Treatment,  with 
Special   Reference  to  the  Skin   Eruptions  of  Children. 

By    H.    RADCLIFFE    CROCKER,    M.D. 

'Physician  to  the   Department   of  Skin   Diseases,    University    College   Hospital,   London 


MESSRS.  P.  Blakiston's  Son  &  Co.  take  pleasure  in  announcing  the 
publication  of  the  new  third  revised  edition  of  Diseases  of  the  Skin,  by 
Dr.  H.  Radcliffe  Crocker.  This  announcement,  coming  at  a  time  when 
recent  progress  in  dermatology  makes  an  authoritative  work  upon  the  subject  a 
positive  necessity,  is  considered  of  special  importance  by  the  publishers,  and  it  is 
believed  the  same  view  will  be  taken  by  the  profession.  Crocker  on  the  Skin  is 
a  book  built  entirely  upon  superior  merit.  It  has  been  acknowledged  by  the 
American  medical  press  as  "the  best  text-book  in  the  English  language."  The 
new  third  edition  maintains  this  high  standard  of  excellence. 

It  is  a  safe,  accurate,  eminently  practical  and  strictly  modern  treatise,  well 
and  clearly  written  by  a  man  of  large  experience  and  most  excellent  judgment. 
Though  completely  scientific,  it  is  written  in  such  a  happy  manner  that  the  tyro 
may  follow  the  writer  almost  as  readily  as  the  expert  on  diseases  of  the  skin.  It 
will  be  seen,  therefore,  that  it  appeals  to  general  practitioners  as  well  as  specialists, 
while  to  the  student  it  will  serve  as  a  valuable  guide  when  he  enters  upon  the 
more  arduous  task  of  practice. 

The  etiology,  symptomatology,  pathology  and  minute  anatomy,  constitutional 
conditions,  diagnosis  and  treatment  of  each  disease  mentioned  is  fully  entered 
upon,  the  therapeutics,  dietetics,  and  general  regimen  coming  in  also  for  their 
due  share  of  attention,  great  strength  in  the  accuracy  of  statement  and  method 
and  clearness  of  definition  and  differentiation  being  shown.  The  newer  remedies 
and  bacteriological  researches,  in  their  bearing  upon  dermatology,  are  carefully 
noted ;  and  particular  attention  is  paid  to  eruptions  as  they  occur  in  childhood. 
This  latter  feature  is  one  usually  much  neglected  in  general  text-books,  and  its 
value  is  the  greater  from  the  known  practical  and  extensive  experience  which  the 
author  has  had  in  this  field. 

The  book  proves  Dr.  Crocker  to  be  closely  in  touch  with  the  work  and 
teachings  of  modern  dermatology  ;  and  he  has  sifted  from  the  vast  accumulations 
of  recent  literature  the  facts  and  opinions  which  have  a  definite  value  and  are 
worthy  of  permanent  record.  The  illustrations,  too,  showing  as  they  do  the 
morbid  conditions  of  the  different  structures  affected  in  diseases  of  the  skin,  are 
a  not  unimportant  feature. 

Many  valuable  additions  to  the  text  are  noted  in  the  new  third  edition  of 
this  standard  work.  The  whole  book  has  been  systematically  gone  over  and 
numerous  changes  made  where  recent  progress  in  dermatology  and  a  more  exact 
knowledge  of  the  subject  has  dictated.  The  result  is  a  work  every  page  of  which 
bears  the  impress  of  honesty,  thoroughness,  and  large  personal  experience. 


Third    Edition,   Thoroughly  Revised,   with  New    Illustrations.      Octavo  ;    1400  pages. 
Cloth,  $5.00  ;   Leather,  $6.00. 

45 


Carpenter  on  THE  MICROSCOPE 

AND  ITS  REVELATIONS 

EIGHTH  ETHTIOff 

Edited  by  W.  H.  Daliinger,  D.Sc,  D.C.L,  F.R.S. 


With  23  Plates  and  nearly  900  Engravings 


OCTAVO.     1181  PAGES.     CLOTH,  $8.00;   HALF  MOROCCO,  $9.00 


*#*  Eight  of  the  chapters  have  been  entirely  rewritten  and  the  text 
throughout  reconstructed,  enlarged,  and  revised  with  the  aid  and  advice 
of  E.  M.  Nelson,  ex-President  of  The  Royal  Microscopical  Society; 
Arthur  Bolles  Lee,  author  of  "The  Microtomist's  Vade  Mecum";  Dr.  E. 
Crookshank,  the  well-known  Bacteriologist;  Prof.  T.  Bonney,  F.R.S.; 
"W.  J.  Pope,  F.I.C.,  F.C.S.,  etc.,  Chemist  to  the  Goldsmith's  Technical 
Institute ;  Prof.  A.  W.  Bennett,  Lecturer  on  Botany  at  St.  Thomas'  Hos- 
pital ;  and  F.  Jeffrey  Bell,  Professor  of  Comparative  Anatomy  and  Zoology, 
King's  College,  London. 

***  A  thorough  and  complete  revision  of  the  entire  text  has 
been  made ;  eight  chapters  have  been  entirely  reconstructed,  and 
everything  of  importance  to  Microscopy  which  has  transpired  in 
the  interval  has  been  noted.  This  applies  to  the  theory  of  the 
Microscope  as  well  as  to  its  use.  Many  new  illustrations  have 
been  included  and  it  has  been  very  materially  increased  in  size. 


CARPENTER"  is  the  only  complete  and  exhaustive  modern  work  on 

the  Science  of  Microscopy 

46 


Diseases  of  ike  Digestive  Tract 

Their  Special  Pathologfy,  Diagnosis,  and  Treatment*  With 
Sections  on  Anatomy  and  Physiology,  Analysis  of  Stomach 
and  Intestinal  Contents,  Secretions,  Feces,  Urine,  Bacteria, 
Parasites,  etc.,  Surgery,  Dietetics,  Diseases  of  the  Rectum,  etc* 

AN  EXHAUSTIVE  SYSTEMATIC  TREATISE 

By  JOHN  C.  HEMMETEK,  M.D. 

Professor  in  the  Medical  Department  of  the  University  of  Maryland  j  Consultant  to  the  University  Hospital  and 

Director  of  the  Clinical  Laboratory,  etc.;  formerly  Clinical  Professor  of  Medicine 

at  the  Baltimore  Medical  College,  etc. 


DISEASES   OF  THE  STOMACH.    Third  Edition. 

With   15   Plates   and  41    other  Illustrations,  some  of  which 
are  printed  in  Colors.      Octavo.      894  pages. 

Cloth,  $6.00  ;  Sheep,  $7.00 

DISEASES   OF  THE  INTESTINES.    Two  Volumes. 

With   19   Plates  and   no  other  Illustrations,  some  of  which 
are  printed  in  Colors.     Octavo.      1421  pages. 

Vol.  I.  Anatomy,  Physiology,  Pathology,  Diagnosis,  Thera- 
peutics, Intestinal  Clinic,  etc.  Cloth,  $5.00;  Sheep,  $6.00 

Vol.  II.  Appendicitis,  Occlusions,  Intestinal  Surgery,  En- 
teroptosis,  Infectious  Granulomata,  Neuroses,  Parasites,  Dis- 
eases of  the  Rectum,  etc.  Cloth,  $5.00 ;  Sheep,  $6.00 

*^*  These  books  form  a  complete  treatise  on  Diseases  of  the  Digestive  Tract. 
The  subject  is  covered  thoroughly  and  systematically  by  an  author  of  well-known 
reputation  and  ability.  The  results  of  recent  investigation,  by  which  so  much 
progress  has  been  made  in  the  Pathology,  Diagnosis,  and  Medical  and  Surgical 
Treatment  of  disorders  of  the  intestinal  tract,  make  their  issue  at  this  time  of 
special  importance.  They  are  handsomely  illustrated,  exhaustive,  and  written 
for  the  general  practitioner,  taking  into  special  consideration  American  habits  of 
living,  diet,  and  climate. 

"  We  wish  to  express  unqualified  approval  of  the  tendency  which  is  shown  to  emphasize  the 
simple  and  more  practical  methods  of  diagnosis." — New  York  Medical  Journal,  Review  of  "  Dis- 
eases of  the  Stomach." 


DESCRIPTIVE  CIRCULAR  UPON  APPLICATION 

47 


NEARLY  READY 


Edgar's  Obstetrics 


A  NEW  TEXT-BOOK 


By  J.  CLIFTON  EDGAR,  M.D. 

Professor  of  Obstetrics,  Medical  Department  of  Cornell  University,  New  York  Cityj  Physician  to  Mothers'  and 
Babies'  Hospital  and  to  the  Emergency  Hospital,  etc. 


Octavo,  about  J 000  Pages;  900  Illustrations 


The  Illustrations  in  Edgar's  Obstetrics  surpass  in  number,  in  artistic 
beauty  and  in  practical  worth  those  in  any  book  of  similar  character.  They  are 
largely  from  original  sources.  Those  which  follow  other  works  have  been 
redrawn  with  modifications  so  that  the  entire  series  is  new.  All  have  been  drawn 
by  artists  of  long  experience  in  this  department  of  medical  illustration,  and 
whenever  of  advantage  to  do  so  are  reproduced  at  a  stated  scale. 

No  attempt  has  been  made  at  display.  When  a  small  cut  serves  every  pur- 
pose drawings  are  not  reproduced  to  occupy  a  large  space;  when  black  and  white 
are  equally  expressive  an  elaborate  colored  plate  has  not  been  used.  So  far 
as  possible,  cuts  have  been  inserted  in  the  text  where  they  are  wanted  and  where 
the  eye  catches  them  at  the  place  the  text  explains  them.  Relative  importance 
has  determined  the  selection,  the  size,  and  the  character  of  each  figure.  There 
are  many  explanatory  diagrams  which  add  greatly  to  the  teaching  values  of  the 
pictures.  The  aim  of  author,  artist,  and  publisher  has  been  to  make  a  series  of 
pictures  useful  to  the  student  and  reader,  and  no  time,  labor,  or  money  has 
been  spared  to  gain  this  end.  The  lack  of  uniformity  in  quality  and  failure  to 
observe  scale — the  great  faults  in  books  on  this  subject — have  been  kept  constantly 
in  mind,  and  every  endeavor  has  been  made  to  avoid  similar  defects. 

The  Text  has  been  prepared  with  great  care.  The  author's  extensive 
experience  in  hospital  and  private  practice  and  as  a  teacher,  his  cosmopolitan 
knowledge  of  literature  and  methods,  and  an  excellent  judgment  based  upon  all 
these  fit  him  specially  to  prepare  what  must  be  a  standard  work  for  both  students 
and  physicians. 

In  the  text  as  in  the  illustrating,  uniformity  and  consistency  have  been  kept 
constantly  in  view.  The  subjects  of  monstrosities  and  malformations,  for  example, 
do  not  take  up  space  which  could  be  better  used  for  more  practical  and  useful 
matters,  though  these  topics  like  others  of  their  class  receive  due  consideration 
and  are  illustrated  by  a  very  complete  series  of  small  figures.  Nothing  of 
importance  remains  unsaid,  and  the  relative  value  of  each  subject  has  been  care- 
fully planned  out  and  fixed  by  deliberate  thought.  The  author's  reputation  is 
sufficient  guarantee  of  the  merit  of  this  book;  the  publishers,  however,  ask  a 
comparison  with  other  works,  with  confidence  that  this  will  be  found  the  most 
useful. 

4?> 


COLUMBIA  UNIVERSITY  LIBRARY 

This  book  is  due  on  the  date  indicated  below,  or  at  the 
expiration  of  a  definite  period  after  the  date  of  borrowing, 
I  as  provided  by  the  rules  of  the  Library  or  by  special  ar- 
I   rangement  with  the  Librarian  in  charge. 


DATE  BORROWED 

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' 

' 

—•* 

C26(238)M100 

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1897 


Richardson      ise  on  *#&**** 

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dentistry 


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